The Bar/Lounge at Royal Lancaster London
Lancaster London's bar/lounge is recommended by expert reviewers. Of the 6 reviews tracked on TripExpert, 2 acknowledged the bar/lounge, like Gayot and Star Service.
Royal Lancaster London 
Gayot
Star Service
Gayot "For dining, guests have a choice between the Island Restaurant & Bar, which serves modern British food, and Nipa, offering reasonably priced and authentic Thai food"
Star Service "Entrances are either from the street (on the far side of the building from the lobby) or downstairs from the second-floor lounge"
