Mario Puzo’s 1969 novel The Godfather was on the bestseller list for 67 weeks, selling more than 21 million copies worldwide. Puzo’s screenplay for the 1972 film adaptation, arguably the defining portrait of the Mafia in the 20th century, contained some of cinema’s most memorable lines – “I’m gonna make him an offer he can’t refuse” among them – and introduced the Italian words consigliere, capo and omerta into the popular vocabulary.

In 1996, the author told interviewer Charlie Rose about being approached soon after the movie’s release by two “ominous” figures – one of them was John Roselli, a Chicago mob assassin whose corpse was later found floating in Biscayne Bay, inside a chain-locked 55-gallon barrel – who insisted that Puzo must have “had access to the top guys” to pen such an accurate depiction of organised crime.