At Your Convenience: A Lavatorial Walking Tour
Royal Festival Hall Steps
Keep walking down the stairs.
Routh goes on to describe all the other 6 floors of loos. My pro tip here, especially for the Ladies, is to head down to the cloakroom on the basement where there is never a queue.
The Royal Festival Hall opened, as Routh said, on 3 May 1951 for the Festival of Britain. The festival was proposed by the Royal Society of Arts to commemorate the Great Exhibition of 1851.