McGOWAN, Circuit Judge:
The central issue in this appeal of a conviction for possession of narcotics (33 D.C.Code § 402) is the propriety of the denial by the District Court, after evidentiary hearing, of a pretrial motion to suppress evidence. The police, confronted visibly with a major narcotics violation in progress, ultimately made a warrantless entry into the house where such violation was taking place, and the evidence in question was forthcoming in the course of the ensuing arrests and searches. The District Court, in ruling against the motion, avowedly took into account the fact that the police, initiating the procedures to obtain a warrant, received legal advice to proceed without one because, in the special circumstances here involved, the delay necessarily inherent in getting a warrant seriously jeopardized the public interest in effective law enforcement. On the record as made, we agree with the District Court that the Government met its burden of showing that the police conduct was reasonable within the meaning of the Fourth Amendment, and affirm the conviction.1
I
We look to the evidence adduced at the suppression hearing. On the first day of that hearing (October 19, 1973), the witness presented by the Government was Officer Simms, of the Metropolitan Police assigned to narcotics investigation, who testified to the following effect.
Not long after 1:00 A.M. on June 14, 1973, Simms was informed by Sergeant Andrews that the Department had just received a telephone call from a person who stated that a large quantity of narcotics was present in the basement of 2918 28th Street, N.W., and that it was visible through the lighted basement window on the right hand side of the front of the house.2 Simms and his partner, Officer Betts of the Narcotics Squad, immediately set out to investigate this report. Not being familiar with the area, they had difficulty finding the house in question arriving there a few minutes after 2:00 A.M. They first circled the house by driving down an alley along one side of the house, observing a ’72 or ’73 Cadillac car parked in the drive[835]*835way at the rear of the house. Completing this reconnaissance, they parked parallel in the street in front of the house, and went up the walkway to the door.
As they did so, Simms observed that, although the rest of the house was dark, there was a light in the right front basement window as reported in the telephone call. With a purpose either to confirm or negate that report, he stepped off the walk to his right — a distance which was later finally established by questioning of the court to be from two to three feet — and looked through the window for not more than 10 seconds. What he saw was the basement bedroom with three men sitting at a table. On the table was a “cutting mirror” and other narcotics paraphernalia used in preparing narcotics for distribution. On the mirror was a pyramid of white powder eight to ten inches high. Simms immediately realized that he was seeing the packaging for sale of a major amount of narcotics (later valued at trial as worth at least $85,000).
Facing what he believed to be a dangerous situation because of the high stakes and the number of persons seen through the window, Simms concluded that it was not practicable to force entry at that time. He and Betts withdrew to their unmarked cruiser where they endeavored to reach their superior officer, Yates, by radio call to the car in which Yates was on duty. This effort was not successful for technical reasons, and they thought it risky, in terms of alerting the inmates of the house to destroy the narcotics, to summon a regular marked cruiser with uniformed police. They immediately proceeded to Headquarters where Simms was able to reach Yates by telephone. It was agreed that Simms and Betts would meet Yates and his partner, Ponzelli, at a rendezvous point (Connecticut and Wyoming Avenues) before returning to the 28th Street house.
While at Headquarters Simms raised the question of getting a search warrant with his superior officers. Lieutenant Ford told him that he (Ford) would call an Assistant United States Attorney while Simms was enroute to the rendezvous point, and that further instructions would be relayed by radio to that point. Ford called Assistant United States Attorney Barcella and apprised him of the situation. Barcella responded that, based on his extensive experience in getting nighttime warrants, it would take a minimum of IV2 to 2 hours to get a warrant, during which time the powder seen by Simms would in all likelihood be removed. Thus Barcella advised Ford that entry should be made immediately without a warrant. He added the suggestion that, if there was likely to be a delay from the first observation to entry of one hour or more, it might be a good idea to look in the basement window again before going in.
Ford sent this information by radio to the rendezvous point and apparently also ordered another cruiser to join the group for greater safety. Thus it was that five officers in all returned to 28th Street. It was Simms’ unshaken testimony that not more than 30 to 40 minutes at most had elapsed from the time he looked in the window until he was back at the house with instructions to enter. The cars were left some distance away, and each of the doorways to the house was covered. Simms noted that the right basement window was still lighted, and that a light also appeared in one of the windows in the upper portion of the house. Betts was at the front door, and Simms and the others went to the kitchen door. Simms knocked first on the screen door and shouted “Police! Police!” When there was no response he gave two or three loud knocks on the door itself. When there was still no response to his repeated calls, he prepared to break the door in when Officer Ponzelli told him not to because there was someone inside looking out through the glass. When this person withdrew and the door was still not opened, it was broken in with a sledgehammer which had been picked up by Simms on his quick visit to Headquarters.
Upon entry one officer went through the first floor to let Officer Betts through the front door. Simms and two other officers immediately rushed down the stairs to the [836]*836basement. At the bottom of the steps they found three men whom Simms, his gun out, ordered to freeze while they were being handcuffed. Simms then stepped through an open door into the lighted bedroom off to his left (the room which he had first looked into through the window). There he found the cutting mirror, but with only powder traces on it, not the powder itself. On the mirror still were the blue and red package tapes, and also on the table were the measuring spoons and pans, and the wrapping paraphernalia. On the floor by the table were distribution envelopes and strainers.
A fourth man was found hiding in a nearby basement closet. Officer Betts, in the basement by this time, found a fifth in the bedroom closet, and a sixth was found hiding in a clothes hamper by the basement stairwell. With the six prisoners secured, a search of the basement was made to try to find narcotics. While the narcotics paraphernalia visible in the bedroom were being collected, bundles of narcotics already labeled and packaged for distribution were found between the mattresses on the bed. In an old rug near the clothes hamper which appeared to have been hastily folded, there was a canvas bag containing a much larger number of bundles of narcotics.3
At the conclusion of Officer Simms’s testimony and cross-examination, defense counsel unanimously signified that they did not wish to examine Lieutenant Ford and Mr. Barcella or any of the other police officers participating in the entry. Neither did they wish oral argument on their own motions. The prosecutor, however, expressed the thought that perhaps Mr. Bar-cella ought to be heard and that, in any event, he thought oral argument desirable. In deference to this last, the court set an adjourned date for oral argument, and asked the prosecutor to submit a statement for the record as to the policy in being at the time of the entry with respect to the availability of the federal magistrates on a 24-hour basis.
When the suppression hearing reconvened some two weeks later on November 1, the prosecutor asked, and was granted, leave to present Mr. Barcella as a witness. Mr. Barcella testified at some length about the procedures for getting nighttime warrants in effect on the date in question, and his experience in advising the police with respect to the need for warrants. Although the police could approach the magistrates directly, the better practice was for them first to have authority to do so from an Assistant United States Attorney; and, indeed, the magistrates would ordinarily, if called by a police officer directly, refer him back to the prosecutor’s office for the handling of the matter.
The magistrate having the duty assignment on the night in question lived “quite a ways out in Maryland in Montgomery County,” and it was necessary either to meet the magistrate at the McDonald’s Restaurant at Eastern and New Hampshire Avenues within the District of Columbia or to go out to his house and bring him back to that point so that he could administer the oath within the District. It was Barcella’s estimate, as stated by him to Ford, that to have done this on the night in question, including the prior preparation of the necessary papers, would have consumed “at least an hour and a half to two hours at the barest minimum.” He had accordingly advised Ford that “if in the estimation of the officers the likelihood of the narcotics not being there after a couple of hours was fairly high, I didn’t think they would have time to get a search warrant and they ought to enter the premises without one.”
In addition to the transportation time involved, Barcella emphasized the substantial amount of time necessarily consumed by the details of getting together the information supporting the warrant and having it typed as an affidavit. He also described certain other forms that have to be prepared and ready for the meeting with the [837]*837magistrate.4 In testifying generally as to his many personal experiences with nighttime warrants, Barcella said that the range of time required was never less than two hours, and on one occasion had taken 5% hours.
The adjourned suppression hearing on November 1 concluded with oral argument and an oral ruling by the court in favor of the prosecution. On November 9, however, the defendants filed a motion to reopen the suppression hearing in order that they might present testimony by one or more of the federal magistrates assertedly relevant to the question of whether the police themselves bore the responsibility for the delays about which Barcella had testified. When the case was called for trial, the court noted as a preliminary matter that this motion was before him. The prosecutor opposed the motion on the ground that what was the defense proposed to show was the physical availability of the magistrates, and that the Government had never contended that the magistrates were not properly available; indeed, the Government was prepared to stipulate not only the fact of physical availability but also that, when the application papers in proper form are submitted to the magistrate, his action would be ordinarily taken within 30 minutes. What the Government had shown, so it was urged, was that the nature of the legal requirements with respect to the warrant application process was such that substantial delay was inherent.
The court, in any event, permitted the defense to put Magistrate Burnett on the stand. He testified from his general experience that, from the time he receives a call from a policeman or an Assistant United States Attorney, “it takes two to three hours if the warrant application is sought at night.” He added that there had been particular instances in which, when the papers were already prepared at the time of the call to him, the time had been as short as forty-five minutes.5 The witness went on to say that the range of time required for nighttime warrants in his experience had been from 5 hours to the 45 minutes just referred to when the papers were in being before the call to him. He testified further that, for the past year or two, the police had had their papers in order when they presented them to him.
II
Appellant, found hiding in the bedroom closet, was one of the six persons arrested in the 28th Street house.6 Each was represented by counsel at the suppression hearing. Several weeks before the hearing, appellant filed a written motion to suppress “all narcotics drugs and paraphernalia” seized at the time of the arrest. The grounds asserted were that the arrests and [838]*838search “at approximately 3:00 A.M.” on June 14, 1973 were “without probable cause, and without a warrant,” and that there was “no reason for the failure of the police to have obtained a warrant.” In appellant’s supporting memorandum of points and authorities, four points were made:
1. There was a delay of more than 2V2 hours from the initial telephone tip to the police and the warrantless entry into the house. “That some delay would be involved in seeking a warrant does not, without more, justify the warrantless arrests and searches here.”
2. “Assuming arguendo that the police had probable cause to make a warrantless arrest when they observed three individuals, not the defendants, in the basement apparently cutting narcotics [see Spinelli v. United States, 393 U.S. 410 (89 S.Ct. 584, 21 L.Ed.2d 637) (1969); Draper v. United States, 358 U.S. 307 (79 S.Ct. 329, 3 L.Ed.2d 327) (1959)] there was no probable cause to believe that some 20-30 minutes later a felony was being committed or that the defendants were committing it. Thus any subsequent search cannot be justified as incident to a lawful arrest. Coolidge v. New Hampshire, 403 U.S. 443, 455 [91 S.Ct. 2022, 29 L.Ed.2d 564] (1971). There was, in any event, no lawful search within the meaning of (Chimel v. United States, 395 U.S. 752 [89 S.Ct. 2034, 23 L.Ed.2d 685] (1969)), given the location of the narcotics and the defendants at the time of the raid.”
3. “At the time of the raid the narcotics were under a rug and under a mattress and hence were clearly not in plain view and subject to seizure . . . ”
4. “The search was illegal because it was based on an illegal breaking and entry without notice of purpose and authority as required by 18 U.S.C. § 3109 >’ 7
The written opposition filed by the Government to these motions recited, among other things, that “John L. Fudge, lessee of a private dwelling at 2918 28th Street, N.W., within which the six defendants in this case were arrested and a large cache of heroin seized, made a then anonymous phone call to police headquarters, reporting the large quantity of narcotics in the basement and stating that it could be seen through the basement window.”
When the motions came on for hearing, defense counsel agreed that counsel for Nelson, Mr. Carl Fogel, could make the opening statement of the defense position for all of them. He did so, and his only reference to the window observation was that the anonymous caller “subsequently was unable to identify at least three of the parties as being in the house at that time.” When he concluded his brief statement and the court asked if any other counsel wished to supplement it, appellant’s counsel replied in the negative, and no other counsel responded.
In his direct examination Officer Simms described his observation through the window, saying that he had stepped off the walkway a few feet on to the grass to do so. On cross-examination, only counsel for Rig-gins and Yarbrough asked about the stepping off the walkway to look in the window, but brought out no more than Simms had already said. The court observed that there appeared to be no dispute that Simms had stepped briefly off the walkway on to the grass. Cross-examination by appellant’s counsel was very brief and did not [839]*839touch on Simms’ peering through the window at all, except to ask how far it was from his point of observation to the powder on the table.
On redirect Simms testified that it was approximately 30 to 40 feet from the street to the basement window, and that he first saw the light as he went up the steps from the street sidewalk to the walkway to the house. The court asked the witness where the window was located with respect to the walkway, and the answer was that “The window is right off to the right of the walkway.” The court then concluded from distance comparisons made from objects in the courtroom that “it (the window) looks to me to be about two or three feet out.”
When the examination of Officer Simms was finished, and after defense counsel expressed no interest in having Officers Betts and Ponzelli placed on the stand for examination, there was the following colloquy between court and defense counsel:
THE COURT: I gather that at least from the thrust of the questions put to the witness that there isn’t any serious question being raised with respect to the means of entry, that is, forcible entry?
MISS McINTYRE: No, Your Honor.
MR. CARL FOGEL: I think that is a fair statement.
THE COURT: And what counsel are presently concerned about is the lack of a warrant?
MR. CARL FOGEL: Yes sir.
When the suppression hearing resumed on November 1, the prosecutor observed, without dissent from any quarter, that “the last time we met, the issue was I thought drawn very distinctly as to Your Honor’s concern and the focus of defense counsels’ comments, and it went primarily to the reasonableness of the warrantless entry.” It was on that assumption, unchallenged by the defense, that he pressed the court to hear testimony by Barcella.
When that testimony was completed, oral argument was had on the disposition to be made of the motions. Counsel for appellant addressed himself solely to the alternatives which he considered were available to Officer Simms at the time he looked in the window, assuming that “he at that point had sufficient corroboration of the type to reach the level of probable cause.” The first alternative was that Simms could— and should — have forcibly entered the house then and there. Second, having chosen to leave the premises for a time, it was imprudent for him to have done so without first having arranged for enough additional police to have staked out each exit from the house. The third alternative was said to be just what Simms in fact did, and that was characterized as unreasonable because there was no assurance of the existence of exigent circumstances, or even of probable cause, when the police returned to the premises.8
In his oral ruling denying suppression at the close of the hearing on November 1 — a ruling which the court saw no reason to alter at the reopened hearing to hear Magistrate Burnett — the court first observed that the facts as related by Officer Simms and Mr. Barcella were “not open to serious dispute.” It considered to be reasonable [840]*840Officer Simms’ conclusion that it was too dangerous to attempt entry during his first appearance on the scene, and it found that Simms’ attempt at that time to consult his superior by radio failed for technical reasons. The court found that 30 to 40 minutes at most elapsed before Simms was back on the scene, and it noted that the evidence of record showed only that the getting of a warrant would have meant a delay of IV2 to 2 hours. It regarded the failure of the police to look through the basement window again when they returned as of slight importance since they were back in such a short period of time. Finally, the court viewed the fact that the police had sought, and received, legal advice as contributing substantially to the reasonableness of the police action in making the warrantless entry.
Ill
It is clear from the foregoing that, for all practical purposes, the case for suppression was presented in the District Court on the theory that the justification for an immediate warrantless entry to arrest and search was attenuated by the absence of the police for some 30 to 40 minutes. That was the issue argued to the court after the evidence was in, and that was the contention it disallowed in denying suppression. It was the same point made by newly-appointed appellate counsel to the division of this court which initially heard this appeal. It was the majority of that division which first canvassed in its opinion the propriety of Officer Simms’ observation through the window. And, although that majority volunteered the view that that observation was improper and could be taken as nullifying all that came later, it concluded not to rest its decision on that ground because it had not been raised by appellant in his appeal.
It is hardly surprising that, when the division opinion was vacated and the appeal placed en banc, appellant, sensitive to the dicta of the division majority, now asks the full court to reverse the conviction on this ground alone. But this belated perception of an issue not theretofore regarded by either trial or appellate counsel as of significance raises the problems inevitably inhering in this disorderly manner of proceeding, such as the compilation of an evidentiary record in the trial court without reference to the legal issue in question, and, even more importantly in this instance, the failure to focus the trial court’s attention upon it in ruling on the motion. Considerations of this nature lie behind the command of Rule 52(b), Fed.R.Crim.P., that matters not brought to the attention of the trial court shall be noticed on appeal only if they constitute plain error affecting substantial rights. Mindful that at no stage of this criminal proceeding prior to rehearing en banc has appellant claimed that any legal injury was inflicted upon him by Officer Simms’ look through the window, we weigh the new call for reversal on this ground by the exacting standard of the Rule.
In his supplementary brief to the court en banc, appellant’s position is stated to be that the phone call received by the police gave Officers Simms and Betts the right to do no more than to go on the premises to make an inquiry at the front door of the house, forcibly to stop anyone who came to the door, and, if there was at that point an articulable fear of weapons, to pat down the person responding to the inquiry. We think, contrarily, that that is an unnecessarily restricted view of what would constitute reasonable police action under the circumstances obtaining in this case.9
In the first place, we note that appellant appears to concede that the tip about the bagging session was a proper subject for investigation by the police, and that that investigation could include going across the premises to reach the house itself. Officer Simms testified that this was precisely what he and Betts did. His testimony further was that, as he and Betts were doing [841]*841this, he saw the light in the right front basement window. This confirmed to an important degree the information supplied by the tip and, again according to Simms, suggested that whether a narcotics bagging session was in progress could be determined conclusively one way or the other by a look through the lighted window. If nothing of that kind were to be seen, then the police could, as Simms testified they would, depart immediately without disturbing the occupants of the house and with a promising lead having come to nothing.
To take that look required a deviation by only a step or two from the course across the yard which appellant admits that Simms was legally traversing. To the extent that that deviation was an entry upon private property arguably differing in its legal significance from the intrusion already in progress, that difference appears comparable to the “mere ‘technical trespass’ ” which the Seventh Circuit, speaking through Judge Pell, said “did not transform an otherwise reasonable investigation into an unreasonable search.” United States v. Conner, 478 F.2d 1320, 1323 (7 Cir. 1972).
In Conner the police were investigating a tip that a certain building was being used for the dismantling of stolen cars. In an effort to see what was going on in the building, the officers went down a public alley to the rear of the building. They were able to see through an open door activity involving the dismantling of a car matching the description of a stolen one. The problem faced by the Court of Appeals, however, was that it was unclear from the record whether the police had been able to see through the door from the public way or whether they had had to go on to the building lot itself in order to do so. As indicated above, the Seventh Circuit was prepared to assume that the latter was the fact, and still to find that the police action was reasonable within the meaning of the Fourth Amendment.
The phrase “technical trespass” used in the Conner opinion was taken from an earlier opinion by Judge Major in United States v. Hanahan, 442 F.2d 649 (7th Cir. 1971). In that case a police officer, using a flashlight, peered at night through the window of a locked door of a garage adjoining a house. The police officer testified that he was standing on a sidewalk on the private property, but one that had been used in such manner as to defeat no expectations of privacy if the police entered upon it. It was contrarily urged, however, that the officer had in fact stepped off the sidewalk onto the grass between the sidewalk and the garage itself in order to be able to look through the garage window. This asserted invasion of the curtilage was argued to constitute the taking of a position by the officer on private property where he had no right to be within the meaning of language used in Harris v. United States, 390 U.S. 234, 236, 88 S.Ct. 992, 19 L.Ed.2d 1067 (1968). The Seventh Circuit, as in Conner, was prepared to accept this version of the facts, but concluded that, even so, there was “no more than a technical trespass on the part of the officer,” not giving rise to any Fourth Amendment violation. See also Atwell v. United States, 414 F.2d 136,138 (5th Cir. 1969).10
[842]*842There is no uncertainty here as to what Officer Simms did. He testified forthrightly that, seeing the lighted window, he stepped off the walkway on to the grass, a distance which the court found not to be more than two or three feet. But, taking into account the nature of the tip he was investigating,11 we, no more than the Seventh Circuit, are disposed to find in this circumstance the difference between reason and unreason in Fourth Amendment terms. Translating these terms into the precise issue before us, we do not think that Officer Simms’s testimony exposed plain error affecting substantial rights requiring us to reverse this conviction.
IV
Given the propriety for purposes of this appeal of Officer Simms’s look through the window, there can be no serious question that, in light of what he saw, he and Betts could legally have entered the house immediately for purposes of arrest and search. This is, indeed, precisely what appellant argued to the District Court that the police were entitled to, and should, have done. The question becomes one, therefore, of whether failure to do so for a period of 30 to 40 minutes dissipated that right, either because at some point in that interval the police could no longer be said to have had cause to believe that a felony was being committed, or because a warrant should have been obtained during the period of delay.
On the evidence of record, we find no irrationality, as neither did the District Court, in Officer Simms’s decision not to enter the house immediately. He testified that he recognized from his quick look through the window that he had come upon a major narcotics distribution operation. Three men were visible in the room, and more might well have been on the premises, all with a stake in resisting arrest by violence if necessary, and in destroying or concealing the evidence. Aided only by Betts, Simms thought he faced a dangerous situation which not only called for careful handling in order not to lose control over the narcotics but also in effecting what might have to be a forcible entry. He tried to communicate by radio with his superior officer for guidance, but failed for technical reasons. He did not think it wise to summon regular patrol cruisers for fear of alerting the occupants of the house that the police were on hand. Under the circumstances, he thought it best to get to Police Headquarters as fast as possible, which he did. There he was directed to rendezvous with his superior officer, with consequent reinforcement, and to await a further order. That order, when it came, was to enter the house, by force if that should prove to be required.
Whatever problems this may leave unresolved about the need for a warrant, the delay of approximately a half hour did not, we believe, terminate the existence of probable cause, any more than such cause would have disappeared at some point in the much longer time required to get a warrant. If it be concluded, therefore, that, under the circumstances obtaining here, the procurement of a warrant was not essential, the police were legally justified in entering the premises when they arrived on the scene the second time, on the basis of what had been learned by Simms on his first appearance there. We turn, then, to the warrant question.
The warrant clause of the Fourth Amendment is, like the other strictures of that charter, subject to the standard of the [843]*843reasonableness of the official action under the particular circumstances. This is not a case in which that action was taken without any reference whatsoever to the warrant requirement, inasmuch as Officer Simms did not ignore the possibility of obtaining a search warrant. During the interval between the first view through the window and the eventual entry, he had discussed this with a police sergeant and a police lieutenant. The latter called an Assistant United States Attorney who, apprised of the circumstances, expressed himself as of the view that the white powder seen through the window was unlikely to remain at the house very long; and he further said that there was insufficient time to obtain a search warrant before its probable removal, inasmuch as he predicted that it would take from one and a half to two hours at the least to procure such a warrant.12
It was only after this consultation that the decision was made to enter the house. The course of conduct followed by the police under these precise circumstances does not seem to us to have been unreasonable, bearing in mind the grave responsibility they have to detect and to prevent activity which the legislature has labeled as criminal. Officer Simms had obviously come upon a very substantial distribution operation of illicit drugs, and the opinion of a prosecutor experienced in the field, coincidentally expressed to the police, was that speedy action was necessary to assure that the values of that observation in terms of law enforcement could be realized.13
The prosecutor’s advice in this instance is not, of course, conclusive. But the action of the police in both seeking and following that advice is relevant to the question of whether the decision by the police to proceed without a warrant was reasonable. The trial judge so regarded it in making his ruling, and we think he was well within the bounds of his discretion in doing so.
Confronted with the prospect of substantial delay if a warrant were to be had, there were other relevant considerations for the police to take into account. First and foremost was the fact that the cutting opera[844]*844tion might terminate and the narcotics be removed from the premises. And it is no answer to the force of this consideration that the police alternatively could have staked out the premises for so long as it took to get a warrant. Stakeouts are full of dangers that the objects of it may thereby be alerted to the presence of the police, and can accordingly destroy or conceal the narcotics, thereby frustrating the police entry when it finally comes.
The panel majority recognized this weakness in the stake-out approach, but turned it aside by refusing to engage in speculation about the probabilities of the destruction of evidence. But exposure to only a few narcotics cases is enough to know that evidence in the form of narcotics is peculiarly vulnerable to speedy and easily accomplished destruction; and that very vulnerability is something that police officers in the course of their narcotics enforcement duties must be unfailingly conscious of and repeatedly speculate about if they are to function effectively to protect the public interest. The District Court had no basis for second-guessing the police on this question, and it can hardly be said to have erred in refraining from doing so on this record.14
There is, thus, no basis for accepting appellant’s contention that, although, in his submission, the police were fully empowered to enter the premises for arrest and search purposes at the time of the original observation of criminal activities in progress, that right was lost upon their failure to exercise it immediately. There was, as was conceded by the defense at the hearing, no impropriety in the manner in which the police entry into the house was finally effected. This leaves only the question of whether the scope of the search, which resulted in the seizure of the narcotics and narcotics paraphernalia,15 was too extensive. This issue, which was not pressed at the suppression hearing nor raised initially on appeal, does not warrant reversal. When the police had seen a crime actually in progress with contraband in plain view, upon entry into the premises they were fully authorized both to make arrests and to seek out the contraband. As the record shows, p. -of 182 U.S.App.D.C., p. 835-836 of 561 F.2d, supra, they found that contraband in the immediate vicinity of the arrests and in the close environs of the point where it had first been seen, albeit hasty efforts at concealment had, as the police had every reason to anticipate, [845]*845been made. Whether the search power in this instance be viewed as incident to arrest, or as deriving independently from the initial observation of the contraband, the materials in issue here appear to have been sufficiently within its sweep to defeat any faulting of the District Court on a plain error basis.
Affirmed.