Bvlgari pool is huge and really stylish. Café Royal is smaller but beautiful. Don't like Haymarket as the pool can double for corporate events, so gets shut down at times - also not as nice IMHO as it is a bit too 'mannered'. Berkeley is small. One Aldwych is not a good hotel, so size of pool is irrelevant. Corinthia is a good 4-star but not in same league as others.