London's often like that these days, I'm afraid. I tend to just search the meta-search engines in the hope of a deal (or leave it for LateRooms if you have the stomach for a last-minute booking...)

If you want a big chain - you mention you have Hilton Gold - I can see a good rate on the Hampton Waterloo at amoma.com and ebookers.com at the moment. Searching Kayak and Trivago are giving a few good offers for that date.