I enjoyed Murano very much - and everyone else I've sent there has come back raving about it too. The Boxwood cafe is pretty average, and I've tried Maze twice and come away 'not getting it' at all.
The Warrington pub is more hit than miss. Plane Food is good by airport standards but would be 'just OK' if on a regular street in London.
Never made it to RHR or Claridges.