The city is a recurring setting in the 007 novels and much of the backdrop to Moonraker (the 3rd in the 007 series), which I re-read in preparation for my tour.

BBC: James Bond��s London

After London, Venice and Istanbul get the most Bond visits, the former being used in From Russia With Love, Moonraker, and most notably in the recent franchise re-launch, the acclaimed Casino Royale.

FORBES: James Bond Is Back: 10 Coolest Places To Find 007