The first opportunity to have the Legation premises thoroughly
inspected for security purposes by British experts, in accordance
with the instructions contained in your Chancery P.I.46/11/7/5 of
29th November 1946, occurred last month after the start of the
Moscow Conference. The United Kingdom Government was successful in
obtaining visas for several technically trained men as members of
their Delegation. On Monday 17th March the Administrative Officer
of the British Embassy brought Messrs. Dunnett and Forty for a
preliminary investigation. Starting their search in the Minister's
office on the first floor, which I have been occupying, they made
their first discovery within ten minutes: a microphone embedded in
concrete exactly at floor level behind the skirting board on one
of the two outer walls. Their first clue was provided by a shallow
groove cut on the underside of the skirting board, and visible
only to an expert eye.

They then temporarily suspended their activities at this Legation,
as they had received instructions to inspect all British and
Commonwealth premises in Moscow, and determine which were wired,
before taking any steps for the disconnection on dismantling of
apparatus or its removal from any establishment. The Legation was
not the first building which they had found to be wired and they
anticipated further discoveries. Their own position was not an
easy one, as by this time the nature of their activities and the
purpose of their visit to Moscow must already have been suspected
by the Soviet authorities, and there was at least a possibility
that their visas might be revoked on some pretext or other. It was
therefore not until Wednesday 26th March that a full inspection
was undertaken here.

Meanwhile various incidents indicated that some Soviet authority,
presumably the MVD, was worried as to what had taken place at the
Legation on 17th March. On Friday 21St March an electrician was
sent by 'Burobin' [1], ostensibly 'to inspect all the electrical
installations in the building'. Such an inspection had never, to
our knowledge, taken place before, so Alexander [2] sent him away
and rang 'Burobin' to say that we were too busy to be troubled
with any workmen in the building for the duration of the
Conference. On Monday morning 24th March the housemaid, while
cleaning the Minister's office, managed 'accidentally' to pull the
wiring of the telephone extension from the wall, a feat requiring
a certain amount of strength and determination, and I was just in
time to prevent a call being put through to 'Burobin' to send
someone immediately to repair it. The most cursory glance around
the room would have revealed to a trained eye that the skirting
board had been removed from one wall and replaced. It was
reasonably certain now that the Soviet authorities concerned were
very anxious to ascertain the nature and extent of our
discoveries, if any. On Tuesday evening 25th March Mr. Bridge,
Administrative Officer of the British Embassy, called to see me to
announce that operations for the removal of all apparatus from the
building would commence the following morning. In the small hours
of the night the direct telephone in the Minister's office rang
continuously for an hour from approximately 4 a.m. to 5 a.m.

Wednesday 26th March. This telephone, which had been installed at
the same time as the switchboard downstairs, was intended solely
for direct outward calls. The number had not been notified to
anyone outside the Legation and yet when the room was empty or
quiet the phone would often ring gently. If one answered one was
greeted either by silence or an abrupt 'Who is that?' but received
no indication of the identity of the caller. Also every night
between midnight and one a.m. the phone would tinkle once or
twice. Our suspicions had been aroused, and I was inclined to
agree with Rowland's [3] suggestion that, if there were a
microphone in the room, the ringing of the telephone, at times
when the room or the house was silent, might provide a means of
testing whether it was working properly.

On Wednesday 26th March Dunnett and Forty set to work about noon
and worked right through until 9 p.m. without leaving the
building, as it was felt advisable to reduce the number of comings
and goings as much as possible. They ate their meals in the room
in which they were working. From the outset the diplomatic staff,
Alexander and Rowland, were informed of the nature of the British
experts' activity and of developments as they occurred. When it
became necessary for them to start work in the offices downstairs
I had to inform the Australian clerical staff, the Crawfords and
Dalton [4], that the building was being 'vetted', but they were
warned not to mention the fact to anyone, and at no stage, either
then or subsequently, were they given any reason to believe that
anything had been discovered. Our two translators, for their own
protection, were told nothing and have asked no questions.

Whatever they may have suspected they know nothing. The domestic
staff, and in particular the housemaid, must have had some idea of
what was taking place by the end of the first day, but there was
little likelihood of their mentioning the matter, except to the
MVD to whom it would be no surprise and who would certainly give
it no publicity.

Within ten minutes of resuming their search the British experts,
by a stroke of luck, located the central distribution point for
the whole house beside the fireplace in the small reception room
next to the Minister's office. (I would refer you to the plan of
the Legation for-warded under cover of our Statement of
Establishment, Staff and Organisation of 20th August 1946. We
relinquished our only copy to the British technicians for use in
the preparation of their report, and they will return photostatic
copies. A plan of the house will no doubt in any event accompany
the technical report which is being forwarded to you from London.)
The mesh of leads was embedded in concrete under the floor boards,
and the concrete had to be chopped away to a depth of several
inches before anything was revealed. From the number of leads it
was clear that there must be 14 or 15 microphones in the building.

(Subsequent evidence showed that there were only 14). The two
which had already been discovered, in the office and the reception
room, like almost all the others which were discovered
subsequently, were set in the wall at the level of the floor
boards, with the wiring below floor level. All were embedded in
concrete which, I am informed, has the effect of amplifying sound,
where wood deadens it.

At this stage an oscillator was connected with the leads and
'buzzed', but only two microphones 'sang', one in my bedroom
(formerly occupied by Mr. Maloney [5]) and one in the small office
off the Chancery, at present occupied by Rowland. This latter
caused a slight stir in the office. The two microphones which
'sang' were those which were furthest from the main distributing
point, at the end of the upstairs and downstairs systems
respectively. It appeared that the Soviet authority concerned,
when convinced that a thorough search was pending, had put high
voltage current through the wires and 'killed' all but two
microphones, with the object of making detection, by such methods
as the oscillator, more difficult. Most of them, when found, bore
evidence of having been 'killed' in this fashion. This had
probably been done during the night of Tuesday 25th - Wednesday
26th March, only a few hours before our investigations were
resumed. The continuous ringing of the 'mystery' telephone in the
Minister's office in silent house in the small hours was no doubt
to test whether all the microphones had been silenced.

The search was completed by 7 p.m. or thereabouts on Thursday 27th
March. Altogether in two days 14 microphones were discovered. By
following the leads back the investigators found the main 'feed'
entering the building through the entrance hall near the
militiaman's shelter. Embedded in concrete under the tiles of the
floor, it crossed the entrance hall and climbed an inside wall to
the central distributing point for the whole house, both upstairs
and downstairs, under the floor boards beside the fireplace in the
small reception room. From there one lead fed the microphone in
the Minister's office. The others crossed the room into the large
reception room and there separated into two main systems, upstairs
and downstairs. The upstairs wires led through the large reception
room to the dining room, and thence to the large room at the back
of the dining room, and back through the second bedroom, breakfast
room and first bedroom. The downstairs system had its distributing
point beside the main door of the Chancery and fed five
microphones, one each in Alexander's and Rowland's rooms and the
entrance hall, and two in the Chancery. Upstairs there were nine
microphones, one each in the office, the small reception, dining
and breakfast rooms, two bedrooms and room off dining room, and
two in the large reception room.

The British experts were impressed with the installation. They
said it was the most carefully installed system they had seen,
elaborately concealed so that only by pulling up floor and
skirting boards could any clue be found, and not necessarily even
then, as all the vital parts were embedded in concrete. They
estimated that it would take two men, working full time, over two
months to install. In Russia it would probably have taken longer
than that. It seems that it could only have been installed when
the building was empty, although the possibility cannot be ruled
out of its having been overhauled and repaired between March and
June 1945, when structural repairs were effected in all the front
rooms on the first floor, following a fire which broke out on Red
Army Day in the small reception room. (See Despatch MU12 of 12th
March 1945). It may or may not be a coincidence that the seat of
the fire and centre of subsequent repair operations was within a
few feet of the nerve centre of the wiring system. I understand
that the floors in the back rooms on the first floor were also
repaired at the same time. The period of the repairs coincided in
point of time with the Minister's visit to Australia (April and
May 1945).

The alterations undertaken by 'Burobin' between October and
December 1946 were limited to painting of walls and ceilings. No
structural repairs were undertaken, except in the main bathroom
and the second-floor bedroom, both of which were free from wiring
or microphones. The workmen were permitted to occupy only one room
at a time and any attempt to remove floorboards would have been
instantly noticed. Neither in 1945 nor in 1946 was any work
performed in the offices downstairs.

I have typed four copies of this report, of which I enclose three
copies. The fourth copy is being retained in this office under
lock and key.

I forward as an attachment to this report the two microphones
which were found in the Minister's office and Alexander's office.

All other microphones, together with samples of the leads, wiring,
concrete, etc., were sent to London for study and use in the
preparation of a technical report which should by now be
completed, and copy of which, together with specimens, is to be
forwarded to you by safe hand from London. My report is intended
to supplement the technical report.

In addition to Alexander, Rowland and myself, the following
members of the British Embassy staff are the only people in Moscow
who are aware of any of the details set out above: the Ambassador,
Sir Maurice Peterson, the Minister, Frank Roberts, two First
Secretaries, R. Allen and D. Macfie, the Administrative Officer,
H. Bridge and the Security Officer Gilmore. Although there were
over 80 foreign journalists in Moscow during the Conference full
secrecy has been maintained. [6]