One of the director’s long-time collaborators was London-born Scot Angus MacPhail - who wrote the screenplay for Whisky Galore. Indeed, it was MacPhail who coined the term ‘McGuffin’ for Hitchcock’s classic misleading plot points.

When Hitchcock’s early 1960s project Marnie became mired in problems – he fell out with his lead actor Tippi Hedren and screenwriter Evan Hunter – the ageing Hitch was in danger of losing his touch.

It’s said this was a time of existential crisis for the director, replacing Hunter with Jay Presson Allen, who had just written an unproduced stage version of Edinburgh born Muriel Spark’s novel The Prime of Miss Jean Brodie.

In 1964 Hitchcock told Allen and Marnie’s star Sean Connery about his lifelong fascination for a play by Scottish writer James M Barrie. It was a whimsical gothic romance called Mary Rose, first performed in 1920.

It tells the story of a girl who disappears on a Scottish island, only to reappear years later without being a day older. She can’t explain where she’s been but, feeling guilty, sets out to look for her son after he has become a man.

‘As a young man Hitchcock had been mesmerised by Barrie’s haunting Mary Rose having seen it in London’, writes Ken Mogg in his book The Alfred Hitchcock Story. ‘Throughout his career he considered directing a screen version and his estate continued to own the film rights long after Hitchcock’s death’.

It’s been labelled the Hitchcock classic that never was, the film he wanted to make more than any other. Plans were in place to film it on location on the Isle of Skye.

Hitch visited Scotland while Presson Allen worked on an early draft of the screenplay (between film projects bon vivant Hitchcock and his wife and long-time collaborator Alma often travelled the world). It was a way to relax, gather up ideas, and scout locations for future projects.

In July 1964 Mr and Mrs Hitchcock, according to biographer Patrick McGilligan, ‘Flew to Scotland for two weeks, visiting Glasgow, Mallaig, Kyle of Lochalsh, the Isle of Skye, Oban, Inverness and Aberdeen – an informal location survey for Hitchcock’s dream project: Mary Rose’.

Hitchcock envisaged Mary Rose as part of a trilogy of strange haunting films about psychological disturbance starring Tippi Hedren. Only two were ever made: The Birds and Marnie.

JM Barrie, who famously wrote Peter Pan, was born in Kirriemuir in Angus in 1860. His Mary Rose is a ghostly Rip van Winkle-like story that has its roots in Scottish folklore.

Celtic mythology is full of tales about children being spirited away by fairies. Some of the eerie quality of Mary Rose can be seen in Hitchcock’s Vertigo, voted by many critics as the greatest film ever made.

When the play was revived in 2017 at Pitlochry Festival Theatre, Scotsman critic Joyce McMillan wrote, ‘Mary Rose is a troubling play that combines a powerful wisdom about the inevitability of death and change with an insatiable, almost sickly, yearning for those who are lost’.

Written in the aftermath of the Great War when so many young men died, the play struck a chord with audiences when it premiered in 1920. It had special relevance to both Barrie and Hitchcock as both had lost loved ones.

Hitchcock’s father died when he was in his early teens and Barrie’s brother was killed in a skating accident. The play, and its theme of death and eternal youth, says much about Barrie and Hitchcock who both had poor self-image were deeply damaged emotionally and had lonely, sheltered childhoods.

Perhaps Hitchcock’s love of the play (and Barrie’s Peter Pan masterwork) was that he saw himself as a boy who wouldn’t grow up. He was, after all, famous for his off-colour jokes and sense of mischief.

Despite a script and pre-production work, Hitchcock never got a green light from any film company to make Mary Rose. Studio executives felt that this fey period drama was irredeemably uncommercial.

Hitch’s fascination with the Mary Rose story never left him. Had it been made the film could potentially have been his most revealing and personal.

One of his biographers, Donald Spoto, even went as far as to say that, “Hitch’s failure to make this film was perhaps the single greatest disappointment of his creative life.”