In the Heat of the Night

A film starring Sidney Poitier and Rod Steiger was advertised in Tube stations during the London Event. The posters described it as "Block-Busters". (TV: The Web of Fear)

Behind the scenes
The poster seen in episode six of The Web of Fear is clearly the poster for, edited — or more specifically "Greeked" — by the production crew to say "Block-Busters" instead of the title of the film.