I know it's not a hotel (and a little touristy) but if you're truly a drinking man I'd recommend the Grenadier in Belgravia
18 Wilton Row, Belgrave Square, London, SW1X 7NR
"A landmark in its own right, The Grenadier is royalty amongst London pubs. This historic treasure chest is not your usual insipid public house. The Grenadier reputation is as illustrious as it is mysterious.
In 1665, the First Royal Regiment of Foot Guards was formed. As a result of the...