Following the Second World War, the town's population greatly increased, with large areas of council housing set up for displaced Londoners, many of which are now in private ownership. Fast train connections to central London have resulted in the town becoming a primarily residential suburb. In 1946, the Admiralty started to build highly secret high-performance electronic digital computers at Borehamwood in a redundant wartime factory, firstly for the purpose of real-time gunnery control, and later for surface-to-air guided weapons and missiles, and for specialist cryptography and code-breaking computers for GCHQ.