No Naughty Bits, Hampstead Theatre
You could call it the BBC Four effect. It's fact-based fictions set in the past, more often than not about the absurdities of sexual mores or other changing customs. In the latest theatrical example, Steve Thompson's new play - which opened last night - we time travel back to December 1975, when the surreal BBC comedy series Monty Python's Flying Circus was due to be broadcast all across the United States. But wait a…