When Marlene Dietrich went to London to make A Knight Without Armour for Alexander Korda, she took a suite at Claridge's.
The set-up there wasn't very convenient for her then-current flame, Douglas Fairbanks Jr (whose flat was on Grosvenor Square): he had to make surreptitious early-morning exits through the servant's halls to get home and keep up appearances.
It didn't take long for Marlene to move out of the hotel and into her own flat, conveniently directly below that of her "Knight". (Fan magazines gleefully reported about the Fairbanks-Dietrich-Sieber roundabout to their readers — and, once Josef von Sternberg was discharged from the hospital where he'd been resting, he joined the troupe on their evenings about town, adding additional spice to the gossip).
Now, the block of flats where Dietrich and Fairbanks stayed, at 20 Grosvenor Square, is being redeveloped. Originally built in the thirties, it was converted during wartime for US Navy use and remained offices until it was vacated in 2007. The developers have already demolished all of the innards (only the façade facing the Square will be retained) and plan on offering about 36 flats for occupation in a few years' time. Stalling the scheme is a disagreement between the developers and the council about the amount of money to be earmarked for affordable housing (not in Mayfair!) pursuant to the development.