Site Records


SiteName: The Rotundas

Marsham Street
London SW1
OS Grid Ref: TQ298790

Sub Brit site visit 28th June 2001

[Source: Bob Jenner]

The 'Rotundas' consisted of three buildings, two of three storeys and one of two (originally five), all linked together and occupying a site in SW1 bounded by Great Peter Street to the north, Marsham Street to the east, Horseferry Road to the south and Monck Street to the west. The site had previously been occupied since c.1877 by the gas works of the Gas Light and Coke Company. The two gas holders were demolished in 1937 leaving two very large circular holes in the ground. During the blitz a large bomb fell on the gas works which blew four workmen into these holes, unfortunately only two survived.

Photo:The South Rotunda in 2001. The building on the roof is an air intake with a small generator room to the left.
Photo by Nick Catford

A government contract was issued to construct various protected buildings in London, these included Montagu House in Whitehall for the War Office, Curzon House in Curzon Street for the Army, The Admiralty Citadel on Horseguards for the Navy and the Rotundas, all designed to withstand the impact of a 500lb bomb. With their 12 foot thick concrete roof the latter complex was equipped to house several thousand Government officials in complete safety from enemy attack for up to three months.

The Rotundas were built in the holes left by the gas holders, each of three storeys with one and a half floors above ground and the same below. They were identified as the North Rotunda at 59-67 Great Peter Street, the South Rotunda at 18/19 Monck Street. The complex was completed by the five storey Steel Frame Building, with one level below ground at 17 Monck Street. The upper three stories were later removed.

1:2500 OS Map showing the two rotundas and the steel frame building

The North Rotunda was built by Mowlem & Co and the South by Higgs Ltd. Work started in November1940 and was completed by 21st June 1941.

The complex was occupied by many different government departments at various different times. The Steel Frame Building (a name by which it was always referred to by the Air Ministry during WW2 and subsequently known as The Citadel) housed the Air Ministry, Intelligence Department AI2(c). GHQ Home Forces occupied the South Rotunda twice. The Ministry of Home Security had its war room in the North Rotunda; this was responsible for all civil defence matters throughout the country through its network of 12 Regional War Rooms. The citadels was linked to Montagu House, The Admiralty Citadel and other Government buildings in Whitehall and beyond by a deep level tunnel. The bottom floor of the South Rotunda also housed the mechanical plant room for all three buildings.

In 1943 Churchill warned about the progress of German plans to bombard London with V-weapons and he reviewed the list of all available citadels in London. The reserve Cabinet War Room at Dollis Hill (Paddock) had proved to be unsatisfactory and too far from Whitehall so a new reserve called 'Anson' was planned for the lowest floor of the North Rotunda. This was ready for occupation on the 15th of November that year together with the Home Office Fire Control (not to be confused with the Regional Fire Control at Horseferry House or the Brigade Control at Lambeth). Unlike Paddock where sleeping accommodation was provided for the Prime Minister at Neville's Court, a converted block of flats a short distance away, Anson was fully self contained with domestic accommodation for Churchill and his senior staff and in theory a direct underground link to Government offices in Whitehall along the post office deep cable tunnels. As there were locked bulkhead doors in the tunnels it is doubtful if this route would have been used with only a handful of Post Office personnel possessing keys.

Plan of Anson
A - MessengersJ - PM's private valet
B - Colonel Ives - Camp Commandant K - BBC equipment room
C - Mrs. Churchill's bedroomL - Maids
D - PM's private secretaryM - Cook
E - Scretary to the War CabinetN - Bedroom for EEB & HLS private secretary
F - Privatesecretary to EEB O - Private secretary to General Hollis
G - Private secretary to HLSP - PM's typists bedroom
H - Commander Thompson (Met Police)Q - Marines
I - PM's personal typist 

At 2.20 am on 19 July 1944 a V1 Flying Bomb landed in Monck Street causing twenty casualties (non fatal) and severe structural damage to the surrounding area. (Westminster Air Raid Report for Abbey District, Post 18 sector 183 Incident No1891 refers)

It is unclear when the name North and South Rotunda was first adopted although it was during WW2, post war they were certainly referred to by that name but the PRO plan of Anson refers to it being on the lowest floor of the North Gasometer. A structure on Monck Street between the North and South Rotunda, sometimes mistaken for an air raid shelter was built as the reception of the dispatch rider service for secret files and documents (PRO file WO199/80)

Further information and pictures about this site continues here

[Source: Bob Jenner]

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