There was a documentary about the coup shown on Channel 4 in the UK in 1985: https://www.youtube.com/watch?v=xhCgJElpQEQ

Just before it was shown, the role of Norman Darbyshire, the MI6 officer involved in the coup, was leaked to the Observer: https://www.theguardian.com/world/2020/aug/02/mi6-the-coup-i...

The Observer received a D-notice which prevented its publication.

The makers of Coup 53 made use of the unpublished Observer material.

Briefly, the UK Government wanted Mosaddegh overthrown because he wanted to nationalize a British oil company (Anglo-Iranian). It tried to get the CIA involved but Truman opposed American involvement. This changed when Eisenhower was elected president.