What Crosby didn’t know was that Kelly was also still seeing actor William Holden (who had an infamously open marriage), as well as Clark Gable and a brief dalliance with David Niven.

Niven famously revealed the affair on the Michael Parkinson show when he recalled meeting Kelly’s husband Prince Rainier of Monaco, who laddishly asked him who had been his best lover.

“Grace, of course,” Niven replied, before hastily adding: “Er, Gracie Fields.”

At the 1955 Oscar ceremony on March 30, Crosby went to Kelly’s hotel room at around 3am, perhaps to distract himself from losing to Marlon Brando for On The Waterfront.

Hollywood commentator Darwin Porter said: “Bing Crosby arrived for a showdown with Grace. Instead of that, he found a nude Marlon in her bed.”

Apparently, the two men came to blows, and then Crosby found himself back on set opposite Kelly from January-March 1956 in High Society.