House of Parliament is south 1/2 mile from the hotel.
Extensive tunnels exist in London - there was actually quite a bit of anon work when the hotel came up back in early Q posts without a name but just pictures and then again when it was specifically posted by Q from post #2794-2800.
Both times there was discussion of the underground tunnels that exist between that hotel and some of the intel locations.
Whitehall is right next door. Ministry of defense police 1 1/2 blocks south. Scotland Yard just after that. So I would expect that entire area to be honeycombed to allow below ground passage and bunkering.
Of course. It all makes sense.
(Not the first time I have shot my mouth off without knowing what I was talking about....)