As an archetypal London location, Trafalgar Square featured in film and television productions during the Swinging London era of the late 1960s, including "The Avengers", "Casino Royale", "Doctor Who", and "The Ipcress File". It was used for filming several sketches and a cartoon backdrop in the BBC comedy series "Monty Python's Flying Circus". In May 2007, the square was grassed over with 2,000 square metres of turf for two days in a campaign by London authorities to promote "green spaces" in the city.