Imagine you are choosing the site for an Underground station. What factors might you consider? For the Great Northern, Piccadilly and Brompton Railway in 1907, there were two. First, they wanted a station in Mayfair. Second, they had a limited budget. The consequence was a station within a short walk of both Dover Street (Green Park) and Hyde Park Corner stations, in an area where the wealthy residents didn't use much public transport, and which was stuck around the corner from the expensive main thoroughfare, on a much quieter side street.
Opening later than the rest of the Piccadilly Line probably didn't help: changes in station layout demanded by the Board of Trade had delayed it by three months. Passengers reached the platforms by lifts and long passageways, slower than the escalator access latterly offered by its neighbours. The surprise is less that Down Street closed in 1932 than that it lasted for 25 years before closing.
However, Down Street didn't stay empty for long. Its new incarnation would see some unlikely features for an underground station: signs pointing to offices; bathrooms and dormitories; and a telephone exchange.
As Britain prepared for the Second World War, the government was well aware of the risk of aerial bombing. It therefore sought deep shelter for crucial functions, and Down Street was chosen to house the Railway Executive Committee (REC). This vital body was in charge of the operation of Britain's railways, ensuring freight, munitions, and personnel could be moved around the country. Its membership included the chairmen of the 'Big Four' railway companies, as well as Frank Pick representing the London Passenger Transport Board.
Where passengers once walked to and from their trains, yellow paint and false ceilings helped create offices, dormitories, executive bedrooms, bathrooms, and kitchens: all amenities required for the staffing of the emergency headquarters for 24-hour operation. Food and furnishings came from the railway hotels. The transformation of the platforms into offices and corridors resulted in some rather narrow spaces.
Crucial to the REC's operations was its telephone exchange, much of which is still in place. It had fifty phone lines, impressive for the period, and a teletype machine.
Secrecy was maintained carefully; even post was delivered to another address and brought here by despatch riders. The REC's activities were carefully screened from passing tube trains. Senior workers were able to hail a tube train from a small section of platform; this was carefully managed so that as far as ordinary passengers could tell, they were simply stopped at a red signal. The Down Street passenger would enter and exit the driver's cab.
Down Street was also the location for Cabinet meetings until the Cabinet War Rooms were completed (thanks to Churchill's aversion to the Paddock shelter). The Prime Minister was not eager to resort to underground shelter, but the supplies of champagne, cigars and caviar from railway hotels no doubt helped console him!
Amenities were divided into three categories: the executive facilities, women's, and 'other workers'. Executives got to enjoy textured wallpapers, still visible today!
Today, some wartime alterations are themselves worn away, revealing the original features underneath. Perhaps most distinctive is the tiling: each Leslie Green-designed station had its own color scheme so that illiterate passengers could recognize their stop. The tiles were concealed under yellow paint; they are now re-emerging, along with some of the original signage.
Other details typical of Green's stations never went away, although they were painted in the ubiquitous (and now-peeling) yellow.
Today, Down Street provides ventilation and an emergency exit for the Piccadilly Line. In other words, usually you would hope not to see inside! However, there have been guided tours in recent weeks as part of the London Transport Museum's Hidden London programme of events - with more to come next year.
There are more photos on Flickr.