(The Security Service)

Architecture in London

Introduction. Possessing a childish interest in secrets; these notes were prompted by the Channel 4 documentary programme "Secret Architecture" and the new "openness" of the Security services.

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MI5's HQ's

1930's 124-26 Cromwell Road.
1937 Transferred to Thames House, Millbank, two floors with 28 staff and later extended to
            offices in Horseferry Road.
1939   Wormwood Scrubs Prison.
Second World War
            Registry, Blenheim Palace, Oxfordshire.
            London Office, 57-58 St. James's Street. Later named Metro House when taken
            over by MGM.
1945    HQ Leconfield House, Curzon Street. Registry on the ground floor.
1976    HQ moved to Gower Street.
1978    Curzon Street House new location of Registry, Administration and Technical services.
1995    Thames House, Millbank.

* Curzon Street House, 1-4 Curzon Street.

MI5 Registry 1976 to 1995.

Curzon Street House. 1-4 Curzon Street. 4th Febuary 1996.

"In 1935 a new thoroughfare called Fitzmaurice Place was constructed in front of Landsdowne House which is to connect it with Curzon Street, but owing to a difference of about eight feet in level of the two thoroughfares [it] is not yet available to though vehicular traffic from Curzon Street to Berkeley Square. In 1939 some twenty-nine old houses situated in the triangular site between Curzon Street, Clarges Street and Clarges Mews were pulled down and Curzon Street House was then erected on this site. It covers an area of over an acre and has lately [c1957] been sold to a property trust for £500,000. Curzon Street is to be widened to fifty feet and opened up into Fitzmaurice Place and Berkeley Square. The stairs in Landsdowne Row will then be replaced by the new roadway which will be available to all traffic."
[7] p209 c1957

"As to what may still be here after the move to Thames House, it's anyone's guess. But a certain mystery will always [be] attach[ed] to Curzon Street House. From his wartime days at Berkeley Street, P. William Filby reports that the building opposite the Mirabelle restaurant 'housed hundreds of pigeons.' Filby never discovered "if and how' the pigeons were used."
[6] p234

The Curzon Plaza Hotel, a new building, still have a "Mirabelle" restaurant.

Bartholomew's Plan of Central London , revised 1974 shows the building marked as Min. of Education.

In the 1948 Post Office Directory, published by Kelly's, Curzon Street House is listed as War Dept. Prisoners of War Information Bureau.

".....the ground floor of the Department of Education and Science in Curzon Street (formerly Beaverbrook's Ministry of Aircraft Production, with it's own self-defence force.)"
[2] p185 and p199 rev.ed.

For good account of Registry, Leconfield House, Wormwood Scrubbs bombing and damaged files, 1955 microfilm copies made and kept at Cheltenham. But muddled Registry/Leconfield House ref.. [5] p37

Known as "The Registry", it housed the records on the windowless ground floor and possibly below. It appears empty now. Note hidden security cameras in the curious canopy. Citadel below. The Royal Family are reputed to have used the building to shelter in during the blitz of the second world war.

For details of Registry Box File procedure, 3 groups, and very labour intensive, female staff etc see
[3] p18

Registry file system
[5] p38.

Female staff known as "Registry Queens"
[5] p39

[5] p39

" was not until well into the 1970's that MI5 finally persuade the Treasury to fund a more permanent, purpose-built headquarters at Curzon House. (Note that Peter Wright does not refer to it as Curzon Street House). Until then the existing overspill problems were dealt with by a succession of short term leases on buildings. Firstly there was Cork Street, which in the 1950's housed the booming empire of C Branch, (Protective Security and vetting of all government installations). Then in the 60's counter-espionage operated from the office in Marlborough Street and we had to pick our way through the peep-shows, flower stalls and rotting vegetables of Soho Market to get to our top secret files."
[5] p36

In 1976, MI5 was "in the process of moving to new offices at the top of Curzon Street.......and had already left Leconfield House for the dismal Gower Street offices".

At first the changes were slight-silly things, like the fact that Hanley, unlike F.J., never offered lifts in his chauffeured car. But then they were more pronounced. We moved offices from Leconfield House, first to Marlborough Street and then to the drab premises on Gower Street. I suggested to Hanley that we go for a greenfield site, perhaps in Cheltenham, but he was insistent that we had to stay in London.
[5] p367

"Gower Street became the HQ; Curzon Street, the new location of administrative and technical offices."
[6] p322-4

Also mentioned as administrative and technical services in Molehunt by Nigel West.

Pevsner, in London 1, remarks that Curzon House is 21-23 and Georgian. Often I have confused Curzon House and Curzon Street House.) Curzon House is a Saudi Arabian diplomatic building.

The demolition of Curzon Street House 1996.
Curzon Street House had been empty for some time. I visited the building on the 4th February 1996 and it would appear that the building is being demolished. The front and side are encased in scaffolding and soon to be covered in sheeting to prevent dust being blown around. The rear of the building was revealing some of the internal layout of the office space.
A crane was in the courtyard and had demolished some of the left-hand wall. One room on the left ground floor seemed to have the walls and the ceiling covered in aluminium sheet. This may have been electronic "screening" for computer equipment to prevent data being "read" outside the room. I think this is known as a "Faraday Box."
I had not looked at the vehicle ramp before. A notice said that visitor's vehicles are likely to be searched ..."by custody guards." The ramp made me think. It's not a big building in ground area. One supposes that the staff for the building would want to remain fairly anonymous and park somewhere discreetly and in safety, especially during the IRA and other terrorist bombing campaigns. So it must have an underground car park of some size. Possibly they converted some of the underground shelter facility in to car parking space?
To the left of the ramp is the gatekeeper's lodge and a single arm barrier and a curious alleyway to the left of the lodge. Looking at the windows one can see that they are all appear to be of shatterproof glass. Some have been damaged during the demolition work and it can be seen that they are not ordinary glass.
The positioning of the building is significant. It's car-park entrance is at the rear and in a cul-de-sac, all very unobtrusive.
Down in Green Park underground tube station is a map of the surrounding streets. Curzon Street House is shown shaded as "MOD."
I visited the site again on the 17th February and took the photos. Scaffold and sheeting have been erected on the front and side but very little more demolition work has taken place to the rear. The crane is still in position and while I was there two maintenance engineers were repairing or servicing the crane. I asked them if the whole building was coming down and they said it was, a new office block was going up. One of the engineers smiled and said that he bet the old place could tell a tale or two, so they were aware of the previous use of the building. I asked if they had found any underground shelters. No, they'd just had a quick look around a saw the 3 diesel generators removed from the basement on the left, they'd only done 20 hours running time. They would be a good buy for someone. I told them that the Royal Family had sheltered there during the war.
Took photos of rear gate-house and control panel for barrier and shutter, ramp, signs and canopy camera apertures. Visited site again on 10th March. Building completely covered in scaffolding and sheeting. Not much sign of any more demolition. Took photos of rear and "1-4" on entrance.
On Saturday 8th July I visited the site again and this will probably be the last sight of the building. Only the northern corner up to the first floor is left standing. The rest of the site was a mass of concrete and iron work collapsed into the basement. The puzzle of the car-park ramp is solved. as that part is still standing and it can be seen that the ramp curves round and the entrance to the car-park is uncovered. One wonders how far it extends. A surprising amount of pipe-work and cabling all tumbled into the basement during the demolition. There was a very large piece of the steel frame laying amongst the rubble, this gives some idea that the building was not just designed as an ordinary office block, and why it was chosen during the war as a secure building. Around at the front I took a photo of the planning application that the demolition company had posted in the boarded-up doorway.
Saturday 15th June, paid another visit. Not much change, except that the front doorway is covered by scaffolding and sheeting. Took a few more of the demolition inside.
October12th, another visit to Curzon Street. The site is now being prepared for building; all the demolition debis having been removed. The contractors, McAlpine, are digging through the basement foundations.

I took many photos during the buildings use by the Security Sevice and later when being demolished. Some have been published.

* Leconfield House, Curzon Street

MI5 HQ 1945 to 1976.

The original old building with NatWest Bank on corner. During the Second World War it was the London District Command HQ.

Machine gun port pointed towards Hyde Park as it was a possible drop zone for German Paratroopers. By the 50's the guns were manned night and day against a mob of  Britons who might stom MI5 from Speaker's Corner. In the 1948 Post Office Directory, published by Kelly's, Leconfield House is listed as War Dept. Command HQ, London District.
[6] p333

"....MI5 had now made the transition from its wartime role...Leconfield House had become the permanent London "office". Steel grilles behind the ground floor level windows, bricked up windows, a curious feature was the gun ports on the south-west corner pointing up Curzon Street towards Hyde Park." [3] p35

The gun ports were at both ends of the building, one also pointed down Curzon Street. My assumption is that they were put in by the military when the building was occupied during the war years by HQ London District Command.

1976 " over to MI5's old HQ at Leconfield House in Mayfair. The organization was in the process of moving to the new offices at the top of Curzon Street."
[5] p2

Mentioned as being in use in 1955.
[5] p56

Brief description of offices, "....teak inlaid corridors and corniced offices."
[5] p3

On part of the top floor was the Pig and Eye Club
[6] p332

The Registry occupied the whole of the ground floor, until it was moved to Curzon Street House in the 70's . Some 300 women maintained the files
[6] p331

"....When Sillitoe took over the DG's office in Leconfield House overlooking South Audley Street...." (30th April 1946 was Sillitoe's appointment as DG of the Security Service.
[3] p26

"...1945 the British Security Service established its HQ after the wartime sojourn at Blenheim. The organization would stay here ....until the 1970s."
[6] p331.

"....undergone many changes since 1972, .....left Leconfield House...."
[3] p177

Laurie says that the building was vacated in January 1978 and the files transferred to Curzon Street House.
[2] p220 rev.edition.

After MI5 left the building was refurbished internally and externally.

On a visit in 1995 I saw a big Daimler car parked outside the building with the licence plate 1 RAC. I wonder if the new occupants of the building are anything to do with the motoring organization or club. Took some photos on 15th June 1996 of the front of the remodelled facade and some of the corner where the supposed machine-gun ports were.

I took many photos during the buildings use by the Security Sevice and later when being demolished. Some have been published.

* 140 Gower Street.

MI5 HQ 1976 to 1995.

Known as "The Russia House". Contains the entrance to Euston Square underground station. MI5 moved to its new Thames House headquarters in 1995.

Peter Wright had an office at Gower Street. The DG's office was on the 6th floor.
[5] p1

Peter Wright mentions the flat on the top floor and he stayed there for his last night in MI5.
[5] p3

Spy's London states that Stella Rimington's office was on the 5th floor. Perhaps that was before she was DG. It would appear that Gower Street became the new HQ after MI5 left Leconfield House in 1975. Curzon Street housed the registry and "administration and technical offices."
[6] p322-4

It was publicized that 2500 staff moved to Thames House
Took photos of 140 Gower Street on October 12th 1996. The building is empty and dirty. To Let signs up. Interesting plate on side door bell. Overhead security camera on small side door at front. Next door is Unity House, the National Union of Rail Maritime & Transport Workers.
Visited Gower Street on 19th June 1998 and took a few photos. All the doorways are boarded up. An A4 sheet stuck in several windows:

0181 579258 "

I took many photos during the buildings use by the Security Sevice and later when being demolished. Some have been published.
One was used in the BBC TV documentary "The Spying Dame"

* MI5 Garages. Banyard Street

Banyard Street mentioned in Spycatcher but Banyard Street Not listed

MI5 garage in Barnard Road in Battersea photographed by soviet agents in 1968
[3] p172.

"......undergone many changes since 1977.....abandoned the Barnard Road garages."
[3] p177.

Mentioning The Counter Spy Shop, 62 South Audley Street, he goes on to say it is, "just round the corner from what were (and still may be) the garages of MI5's watchers."
[6] p336.

* South Audley Street.

".....undergone many changes since 1972.....left.....their (IRA) bombed out-office......"
[3] p177.

* 33 South Audley Street.

Here Sir Roger Hollis was interrogated, in the 1960's, by MI5's molehunters.
[6] p336.

"33 South Audley Street, the 'wired accommodation' in Mayfair where Graham Michell and Sir Roger Hollis underwent a detailed interrogation the hands of MI5's molehunters."
[8] picture caption.

* 72 Grosvenor Street.

Harry Hunter and later Jim Skardon watchers office.
[3] p136

* Berkeley Street

....... followed by the usual five-month series of lectures at the Security Service training centre in Berkeley Street, Mayfair.
[8] p151

* Dollis Hill.

"....Dollis Hill the rather ugly Victorian building in North London where the Post Office had its research HQ in the 50's. John Taylor ran his mail experimental laboratory for MI5 and MI6 in the basement behind a door marked "Post Office Special Investigations Unit Research".
[5] p46

During the Secone Worl War Dollis Hill was also the location of Churchill's PADDOCK bunker, should the Cabinet War Room in Whitehall become untenable

* Horseferry Road.

1938, MI5's HQ.
[3] p140

Pre-war staff totalled only 92. see text for details
[3] p141.

"On 26th August 1939 MI5 moved all staff to Wormwood Scrubbs prison but it was unsuitable and in May 1940 moved all non-essential departments to Blenheim Palace. Vital departments took over
a large building in St James' Street."
[3] p141.

Moved to Wormwood Scrubs prison, photo of "B" Hall
[4] p63

The next move was to Blenheim Place which became the main Registry while MI5's London office was established in St James' Street. The move to Blenheim Palace was still under way when a German incendiary bomb struck Wormwood Scrubs and a considerable part of the records were damaged. MI5 had spent a lot of time and money microfilming its records to guard against just such an eventuality. However many of its files turned out to be over-exposed and completely useless. Peter Wright recalls in Spycatcher searching trough charred files.
[4] p62

At first I thought that this was a puzzle as this is the move to Broadway Buildings, a building occupied by MI6. but this is clarified by West; "Contrary to Sir Findlater Stewart's recommendation of November 1943, MI5 had not moved in to shared accommodation with the SIS-MI6"
[3] p35.

"Used Blenheim Palace in Oxfordshire to house some of its administrative offices-also a number of smaller offices in London, in Regent's Street, Piccadilly and Dolphin Square where individual case Officers could meet their agents."
[3] p19

At the end of the war plans had been drawn up to create a joint Headquarters of Intelligence to house both services. A site for the premises was even acquired in the Horseferry Road.....The situation remained unsolved until the 1960 when MI6 were finally banished across the Thames in their own building, Century House.
[5] p35.

* Post Office Special Investigations Unit.

"...outstation was the HQ of the Post Office Special Investigations Unit near St Pauls, MI5 had a suite of rooms on the 1st floor...later the laboratories were moved to the Post Offices Laboratories, Martlesham, Suffolk."
[5] p45

* Thames House, 11 Millbank.

MI5 HQ since 1995

For description of the building see "The Buildings of England" Pevsner.

"...Thames House on the west side of Horseferry Road, consisting of two blocks of buildings joined by an overhead bridge across Page Street.......were designed by Sir Frank Baines FRIBA. Thames House, which is claimed to be the finest office building in the British Empire, has a frontage to the river of 500 feet and contains no fewer than eighteen lifts, capable together of carrying 250 passengers at a speed of 400 feet per minute. These two buildings were erected within the short period of three years, between 1929 and 1931.
[7] p234

"Imperial Chemical Industries House and its neighbour Thames House were designed by Sir Frank Baines and built between 1929 and 1931. The doors have no locks, being operated by electrical power."
Discovering London Curiosities. John Wittich. Shire Pub 1990

MI5 had occupied two floors of the building in 1937, all 28 staff! They had transferred from Cromwell Road.
[9] p48

At the outbreak of the Second World War MI5 employed about 75 officers and occupied the entire top floor of Thames House.

The new MI5 headquarters.

The building was purchased at the height of the property boom and cost the security service £100 million. Today it is thought to be worth only half that figure.

"...and an ICL computer installed in a data processing centre close to the new HQ."
[3] p177

The following item, by Rowland Morgan, appeared in the "Digitations" column of the Guardian Weekend, December 16 1995.
"Cost of the rock-face wall in the trophy room of the MI5 secret police headquarters at No 11 Millbank: £25,000."
"Source: HoC Official Report, vol 267, no 5, col 506.

" Visited the building on the 15th June 1996 and took photos. The new entrance with a central flight of steps and beside that a pair of slopes. To the rear is the vehicle entrance and underground car-park. While I walked past the gates slid open and I could see into the entrance. There was a sign-board with: ALERT STATUS: BLACK SPECIAL the words "BLACK" and "SPECIAL" could be changed by sliding in different boards. Many cameras covering all sides and approaches. Some with infra-red lights. The building has emerged scrubbed and modified after many months behind the scaffolding. One surprise and confirmation of the new openness was the flag flying from the flag-pole with the new logo

MI5 Order of Battle.
[3] p19.


[1] BBC2 TV "Secret Architecture"  Jonathan Meades-1993
[2] BtCS - Laurie
[3] M of T - West
[4] MI5-MI6 - Grant
[5] Spycatcher - Wright
[6] A Spy's London - Berkeley
[7] The Face of London - Clunn pub c1957.
[8] Molehunt - Nigel West
[9] MI5 - Nigel West
[10] MI5: British Security Service Operations, 1907-1945. Nigel West
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