The square, home to Oleg Deripaska, Russia's richest man, is also the long-term home of the IPA. It has never moved because of the generous terms of its lease.
Eight years ago, when the IPA first mooted the idea of a single "supergroup" to become the voice of the UK's entire communications industry, it calculated it could raise up to £4 million by giving up the Belgrave Square lease. Intriguing to know what that figure might be now should it choose to cash in.