"For everyone who's seen the Bond movie Die Another Day, we see a supposed secret 'Vauxhall Cross' station. Truth however is very often stranger than fiction. Whilst Vauxhall Cross doesn't exist, there are rumours however that there WAS a secret station for MI6 to transport its staff to its Westminster Bridge Road headquarters (from the mid 60's until their move to Vauxhall Cross in the 90's).
"The building - now apartments - is only a stone's throw from Lambeth North station. However one of the people involved in the redevelopment of the property noted it was a rather interesting project. The Bakerloo and Northern lines cross diagonally beneath the building, and when asked by the developers whether any other tunnels were below the building, London Underground were said to be 'noticeably evasive'!!!
"MI5 officer (and would-be traitor) Michael Bettaney made several (unsuccessful) attempts to contact the KGB in central London in the early 80's. One of these involved asking his Soviet target to leave a drawing pin ('any colour'!) at the top of escalators 3 and 4 in Piccadilly Circus station if he wanted to arrange a meet. Luckily for us we had MI6 asset Oleg Gordievsky in the KGB's London station who told the Brits what was going on, pronto.
"Also during the Cold War, there was a belief among Russian intelligence officers that our security services looked out for spies behind the large advertisements bedecking tube stations.
"Finally, the tube stations Kew Gardens, Mornington Crescent, Pinner, Piccadilly Circus - have all played their part as rendezvous points for Soviet agents and their handlers in decades past."
So next time you see someone in a raincoat with a packet of drawing pins lurking around the top of escalators, throw them a googly by saying "The Portuguese newt is crouching on the eastbound platform" and see what they do!
If you've any other spy or espionage story about the Tube, leave it in code in the comments below.