Here?s an interesting thing that I?ve turned up in connection with a
secret trial held at the Old Bailey in 1940. (Well, I think it's
interesting, anyway.)

In a pre-trial statement (probably prepared for the DPP), Detective
Inspector P of the Special Branch implied that he had ?led? a search
party on a suspect?s premises. The party included Captain X, a MI5
Officer. Inspector P later took the suspect to Cannon Row Police
Station where he was detained.

However, according to the Trial Transcript, Captain X testified that
he had searched the suspect?s premises with Detective Inspector K, who
had a search warrant.

There is compelling corroborative evidence that Detective Inspector P
actually was on the search party although he never appeared at the
trial.

There is also corroborative evidence that suggests that Detective
Inspector K was not on the search party.

Possibly Detective Inspector P was sick on the day that he was
required in court and Detective Inspector K deputised.

The defendant was found guilty, largely upon the fruits of the search.

Evidently, no one picked this up at the time (or since until now) but,
if they had, would it have mattered trial-wise?

The opinions of one (or more) legal guru(s) would be appreciated. 

Many thanks.

Bryan
Rather difficult to say from what you have said so far (I am a former
police officer). There are a host of clarification questions I could
ask.
What was the search warrant for?
How many were involved in the search?
What incriminating items were found?
Who found them? 
Did Insp.K state in his evidence he was on the search?
Did Insp.K find any of the items? 
Did the defence accept that the items were found on the premises as
stated by the officers or did they allege they were planted? If they
accepted they were found, they may have requested Insp K (in absence
of Insp P) to have him answer some questions which the defence wished
to have in evidence in their favour i.e. "Was my client co-operative?"
"What was the layout of the house" "Did my client tell you to speak to
a neighbour who could clear his name" - that sort of thing.
What is the nature of the corroborative evidence against Insp K, and
was this put to him in trial?
If Insp P?s evidence was that vital, the defence could have argued for
delay of the trial until he was available.
I don?t think I can answer it ( or research it) as the law has changed
considerably since then, but I?ll certainly give you a comment.
answerfinder-ga

Going only from what has been submitted here, it would depend on
whether either Inspector P or Inspector K gave evidence for the
Prosecution at the trial. If neither was called, then one could merely
point out that Captain X's evidence was at variance with the pre-trial
statement. That might go to demonstrate reasonable doubt, if one could
call the accuracy of Captain X's evidence into question. If he made a
mistake in that point, it is possible that he made an error at other
points. One might, one supposes, also question whether an illegal
search was made prior to obtaining the warrant, in order to gather
cause for the warrant, and this double search was the source of X's
confusion. If he simply made a mistake of names, however, it wouldn't
mean anything.

It might be useful to the defense to call either P or K, but that is unknown.

hlabadie-ga

Many thanks Answerfinder & Hlabadie for your comments.

I don't know any details of the Search Warrant; however it is NOW (but
not then) apparent that Captain X had searched the premises
previously. Whether this was illegal or not, I can't say but I would
bet that it was.

There were 5 people in the Search Party according to one version; 4
according to another.

There was a mass of incriminating evidence, most importantly lots of
documents that the defendant had taken from his employers.

I don't know who found them and Captain X was never cross examined on this matter.

Inspector K did not give evidence on this matter either, although he
did give evidence on a later day on some other matter which appears
irrelevant.

There is nothing to say that Inspector K was actually present at the
Search or even in court on the day in question. If Inspector P was in
court, he certainly was never called.

The Defence simply accepted Captain X's statement in court, so
Inspector K was never interrogated on this matter.

The pre-trial statement has only come into the public domain recently
following the release of files into the National Archives.

I have the impression from some other stuff in the trial transcript
that the Defence Counsel wasn't really trying. (A Perry Mason he
wasn't.)

I should add that this case is very unusual because a transcript has
become available in the public domain and it is apparent that this
possibility was not anticipated by the Prosecution. For example, the
MI5 officers and agents appeared under their own names.

Please let me have any further observations that occur to you ...

Of course, I was rather hoping that you would have screamed 'Fix' -
which it probably was.

Bryan

Is it possible that the stenographer made a simple transcription error
and wrote K instead of P on the trial transcript by mistake? Would the
transcript still be consistent if it referred to P?

Hi, Eiffel

'Twas I that reduced the names of the two 'tecs to mere ciphers.

The name of P was spelled out, with his two initials, in the Pre-Trial
Statement; the name of K was spelled out, with his Forename, in the
Trial Transcript.

In fact, there are TWO different Trial Transcripts and they differ
only occasionally with what are typos.

Bryan

Possibly, the Search was not relevant, after all, because the
defendant had made a statement in which he admitted having the
evidence in his possession?

However, the statement had been given to Captain X who was not a
police officer but maybe that didn't matter either?

Who cares , you need to get out more..

Bryan
These are my thoughts:
I think you have summed it up with ?The Defence simply accepted
Captain X's statement in court, so Inspector K was never interrogated
on this matter.?

My reading of it is that the defence took the view that the exhibits
were lawfully seized and decided not to challenge their finding. Also,
the defendant had made a verbal admission to Captain X that the
exhibits were in his possession. Captain X's evidence would be
admissible at this time (1940s).

For the first search Captain X may have been acting under special
war-time powers which allowed him to search (I have no information on
this), or he had the defendant?s permission to search but could not
proceed further as he had no power to seize the evidence. Therefore he
had to inform the police so that they could obtain a search warrant.

At the trial, the defence would have been in possession of the
pre-trial statement, the witness statements and would have been
entitled to view the officers? notebooks on the search. However, it
was not until the late 1980s that there was such thing as ?advance
disclosure? by the prosecution to the defence of what is termed as
?Unused Material?. That is all material which does not form part of
the Prosecution case but was seized by the police or prosecution
during the course of their investigation.

Whether the defence were aware of the inconsistencies of the two
Inspector?s evidence from the documents in their possession I cannot
say, but they seem to have taken the view that the search was lawful.
Even if the Inspectors? evidence was challenged, Captain X could give
evidence of the existence of the exhibits in the defendant?s house. If
they had challenged the two inspectors? evidence and found
discrepancies, the judge would have had to consider the seriousness of
the discrepancies and pass an opinion on their actions and whether the
evidence should go before the jury (actions ranging from attempted
perjury to genuine mistake). If they were minor discrepancies,  they
would be allowed in evidence because the documents were seized
lawfully and were capable of being used as evidence in the trial.

I should add that the law has changed dramatically on this since the 1940s.
No research on this apart from this recent judgement which does give
some background on the law of arrest and search (without warrant) and
Common Law searches. The rest in my opinion as a former police officer
from the early 1970s to 2001
http://www.parliament.the-stationery-office.co.uk/pa/ld200102/ldjudgmt/jd020516/rott-4.htm

Also from my own experience, in court the prosecution pre-trial
statement may vary from the actual evidence given if the witnesses do
not come ?up to proof? in their evidence. Finally, mistakes are always
made in court trials on small details. Mistakes are made not only by
witnesses, but by judges and barristers. Some are noticed, others go
by unnoticed and appear in the transcript. It is human nature. This
may account for the 4 or 5 people in the search party.

answerfinder-ga

Hi, Again, AnswerFinder

Brilliant comment.

Many thanks.

Would you now like post an Answer?

Bryan

Bryan,
Thank you for your kind offer but on this occasion I'll leave it as a
comment. I would prefer to have given an answer with good sources
instead of a comment from my own experience.
Perhaps I'll get to answer your next interesting question (as they always are). 
answerfinder-ga

Aw, AnswerFinder

Aren't you nice?

Very many thanks & my warmest regards.

Bryan