The building, which was completed around 1924, the main operating base of MI^ - British Intelligence - until they moved to Century House in 1964. MI6 is the foreign intelligence service of the British government, as apposed to MI5 who handle domestic intelligence spying. It is said that when MI6 initially moved in under cover of the Minimax Fire Extinguisher Company, local taxi drivers soon figured it out, and that knowledge soon passed to foreign spies. The Streetview is pixilated, however this is a user submitted Photo Sphere image.
Government - National - Foreign, Buildings - Government, Military - Censored
Links: en.wikipedia.org, en.wikipedia.org, www.sis.gov.uk