That's always been the case. You have 10 floors in Blackburn. Moreover, you have all sorts of other buildings.
Clearly, the public service is not unaware of the fact that, when meetings take place in the Prime Minister's Office, it sends a message. If you want to send a message that this foundation is closely connected to the Prime Minister and therefore donations to this foundation are appreciated by the Prime Minister, a great way to send that message is to have it in the relatively small building that is called “the Prime Minister's Office”.