I can accept the pilot's issue here, if e.g. a bunch of people have a party in the room next to his and can't sleep all night he can call it: 'not fit to do my duties, not fit for my flight!'. Perfectly legal. It's occassionally though that a pilot (or cabin crew) calls on this aviation rule...
No, I guess that BA rents constantly a certain amount of rooms at that hotel for a fixed price. When the room is not used , the hotel sells the room for full price.Could be unregistered guests, extra income for night staff. ( black income ) Happens a lot.
Apparently there was a large cricket match with a loud PA system in close proximity to the hotel, with loud music being played late. Add to that a main railway line and train station next to the hotel and you should get the picture.
Now the spokesman of the hotel chain said that the crew partyied all night. How elegant from them !