“My God!” Hitchcock exclaimed to screenwriter Howard Fast. “I’ve just seen Michelangelo Antonioni’s Blowup. These Italian directors are a century ahead of me in terms of technique. What have I been doing all this time?”

Shocked into the new, Hitchcock repeatedly watched Blowup. Test footage for Kaleidoscope – the project that would become Frenzy – is suffused with similar dreamy colours and jaded infatuation with swinging London.