Nos. 10-22 Portland Place (marked in red above and seen from gound level below.)
No.10 was the home of an old lady who would not leave her house. This held up building for a number of years. No.12 was occupied by the Central Council for Schools Broadcasting. No.14 was the home of the Radio Times and a warren of passages ran between this building and No.18. These passages lead to accommodation for OBs Department, the Empire Service announcers (complete with sleeping quarters) and Children's Hour. - G.S.
A special feature of the extended elevation was to be the semi-circular treatment of the corner of Portland Place and Duchess Street, surmounted by one of the masts removed from the existing building. This shape was presumably meant to be an echo of the front of BH. - G.S.
The new extension would more than double the size of BH. The site area at ground floor level was 20,950 square feet, compared with 17,390 square feet of the existing building. The architectural treatment, which was approved by the Royal Fine Art Commission, was planned to continue and amplify that of the existing facade to Portland Place, the two portions of the building forming a complete architectural entity that would be both dignified and in harmony with its surroundings.
Above ground level the building was planned to provide mostly office space. A new control room would be built on the seventh floor, meant to supplement, not replace, the existing one. A restaurant would be provided on the eighth floor with accommodation for nearly three hundred people. A light court would occupy the centre of the structure. Below ground level the plan provided a general purpose studio 80ft x 54ft by 30ft high, three dramatic studios, an effects studio and a number of rehearsal rooms. More than a million cubic yards of earth would need to be removed and the depth to which the building would go - fifty-four feet below pavement level - would be lower than the vaults of the Bank of England. The resulting excavation would have a capacity of nearly ten million gallons of water. By December 1938, 'Practical and Amateur Wireless' was reporting that Messrs. Higgs and Hill Ltd had been awarded the contract for the excavation and for the erection of retaining walls around
Instead, work started on what was to be a 'complete broadcasting station in miniature' built underground along Duchess Street. This structure was known as 'The Stronghold' and contained studios, a control room, recording rooms and offices, all under the shield of a concrete roof 9ft 6in thick.
Completed in November 1942 and linked by line and radio to transmitters at Brookman's Park and Daventry, the Stronghold was intended for emergency use - but fortunately it was never needed since although the main Broadcasting House was bombed on several occasions, it did not sustain damage serious enough to cause loss of programmes. The worst damage occurred on 15th October 1940, when a 500lb bomb landed in the music library, killing seven people. Bruce
The Stronghold figured as a kind of last resort, along with Wood Norton (near Evesham, Worcestershire) in the BBC's planned scheme for evacuating studios. According to a document entitled 'Emergency Evacuation of London Premises', undated but almost certainly prepared in October 1942:
"The Stronghold and premises at Evesham are general reserves for all services. Within the limits of accommodation and facilities available, the Stronghold is a last reserve for any or all of the Corporation's services. It is also equipped so that Home News, News Talks and Presentation, could transfer to the Stronghold as soon as News Agency and Recording facilities were provided. (The Stronghold is reached through the gas-proof door, LG2, opposite the Lounge, on the lower-ground floor in the north-east corner of Broadcasting House. Keys are in the possession of the Duty Officer, Duty Room, B.23). Moves to Evesham or the Stronghold will be decided by the Director-General in the light of prevailing circumstances."
In a once secret internal BBC memo it was noted that the Ministry of Works had inspected the Stronghold and reported that "...its chances of surviving an air burst bomb of the Nagasaki type would be rated very high." - G.S.
alignment. Built into the Stronghold is a door with a staircase leading down and ending in a brick wall, planned to give access to the basement level of the Broadcasting House extension originally intended. Incidentally, the Stronghold is the same protected accommodation that Peter Laurie described in Beneath The City Streets but mistakenly assumed to be at the Maida Vale studios.
Notes by Andrew Emmerson, adapted from material in his book 'London's Secret Tubes' published by Capital Transport Publishing.
Les "LG" Smith provides this footnote:-
At the time the Stronghold was built considerable thought was given to ensure that it could be incorporated into the BH Extension as it was being planned in 1937/8. My understanding was that the position of the Stronghold was that planned for the cashiers' office, which would require secure concrete walls similar to the construction of banks. The foundations of the Stronghold were planned to support the weight of the proposed superstructure of the Extension and consisted of 58 cored piles. The roof of the stronghold was augmented by a top layer of concrete blocks about 4x4x4 ft. with lifting eyes built into them so that they could be easily removed after the war.