Page "Room 40" Paragraph 26

Once the new organisation began to develop and show results it became necessary to place it on a more formal basis than squatting in Ewing's office.

On 6 November 1914 the organisation moved to Room 40 in the Admiralty old building, which was by default to give it its name.

Room 40 has since been renumbered, but still exists in the original Admiralty building off Whitehall, London, on the first floor, with windows looking inwards to a courtyard wholly enclosed by admiralty buildings.

Previous occupants of the room had complained that no one was ever able to find it, but it was on the same corridor as the Admiralty boardroom and the First Sea Lord's office ( Sir John Fisher ), who was one of the few people allowed to know of its existence.

Adjacent was the First Lord's residence ( then Winston Churchill ), who was another.

Others permitted to know of the existence of a signals interception unit were the Second Sea Lord, Secretary of the Admiralty, the Chief of Staff ( Oliver ), the Director of Operations Division ( DOD ), assistant director, Director of Intelligence Division ( DID, Captain William Hall ) and three duty captains.

Admiral Sir Arthur Wilson, a retired First Sea Lord, had returned to the admiralty to work with the staff and was also included in the secret.

The Prime Minister may also have been informed.