This is a strange one, as it’s the only station on the list that never even made it to being a station. It was built on the Northern Line (then known as the Charing Cross, Euston and Hampstead Railway) between Hampstead and Golders Green in 1903 and would have been the tube’s deepest ever station. But only the lower levels were completed – in 1906, building stopped and the project lay redundant until the 1950s when a surface building was built, along with the access down so that it could be used for storage.But although no passengers ever alighted here, it saw its share of action. Trains still passed through the ghost station in the early days, with few passengers aware of what should have been there, and in World War II it was used to store secret documents. With no surface access, it was the ideal secret store and it could only be visited by service trains.The station was pressed into service again during the Cold War – at such a deep level underground, it was deemed to be the perfect control center from which to manage the emergency floodgates of the tube. The surface building was disguised as an electricity station, with appropriate signs, and the exits were exits not only from the station but from the whole tube network. Clearly someone’s Cold War plan involved everyone sheltering in the tube and then calmly filing out onto Hampstead Heath. Very British!In another mark of very Britishness, the alternate name (“Bull & Bush”) comes from a nearby pub. It never opened, but still had enough people working there to get itself a nickname!