Anthony Hopkins and Helen Mirren in <i>Hitchcock</i>.

Anthony Hopkins and Helen Mirren in Hitchcock.

Like Margaret Thatcher, Alfred Hitchcock was the child of an English greengrocer. Unlike the Thatchers, who were strict Methodists, the Hitchcocks were Catholic. Alfred attended Catholic schools in London staffed by men who didn't spare the rod. At the end of his life he was still dwelling on it.

"First you would be told how many strokes you could expect," Hitchcock told David Freeman, the last screenwriter to work with him before he died in 1980.

"Then you were left to consider that amount until such time as you chose for the blows to be administered. A boy would naturally put it off and that only increased the agony … The sting was absolute. I can feel it now."

It's unsurprising, then, that the Sacha Gervasi-directed biopic Hitchcock shows the protagonist, played by Anthony Hopkins, as a man tightly bound within the scar tissue of longstanding wounds. As well as the school thrashings, Hitchcock's psyche was seared with the memory - whether real or imagined has never been ascertained - of his father getting him locked up briefly in a local police station cell after a very young Alfred misbehaved. Then there was his portly stature which among other things led to his rejection for military service in World War I. Being broad in the beam didn't stop him getting a smashing wife, though, and it's the period of his long marriage to Alma Reville coincident with the making of Psycho (1960) on which the film Hitchcock focuses.

Helen Mirren plays Alma in the film. At its start Alfred is 60, drinking steadily, mooning about in search of the next project and worried that people think he's over the hill. Alma's womanly impact on him has eroded to zilch. He can't even muster the requisite compliment that keeps the wheels of longstanding marriages oiled when Alma, off to lunch with a friend and showing off her outfit, asks him how she looks. D'oh!

Hitchcock was legendarily obsessed with blue-eyed blondes, pursuing them inappropriately and in some cases - Tippi Hedren being the best known example - persecuting them professionally after rejection. Hitch could be to uncooperative screen ice queens as Lance Armstrong was to team members resisting EPO: downright nasty. While Alma and Alfred had a daughter, Pat, born in 1928, the Hitchcock marriage appeared to have become sexless by the time Hitchcock begins. It was not loveless, however, and Alfred and Alma were in their own way intensely devoted, not least when it came to the business of making movies.

One of Hitchcock's best scenes reenacts the shooting of the famous "shower scene" from Psycho - worth the admission price alone for the insight it provides into Alfred's psyche but, even more, for what it suggests about successful directing. Janet Leigh, played in the film by Scarlett Johansson, isn't acting in Psycho - she's genuinely terrified.

Another of the best scenes doesn't include Alfred at all. It's when Helen Mirren's Alma quietly walks onto the set and takes control of the film after Alfred collapses from exhaustion. She sees off the studio boss opportunistically out to replace Hitchcock with a lesser director and slots straight into the director's role herself. After all, as Alma points out in Hitchcock, when they first met she was Alfred's boss - an editor and assistant director while he was still making his way up the ranks.

That Alma is the great unrecognised collaborator who helped make Hitchcock films what they are is an important takeaway from the film. On Psycho alone, for example, she picked up and got fixed a lethal continuity error (Janet Leigh visibly swallowing after Tony Perkins' character, Norman Bates has murdered her) and oversaw a major re-edit of the film after Hitchcock's first cut flubbed out with the studio bosses. On Strangers on a Train (1951) she was one of the three-woman team who wrote an entirely new script at high speed after Hitchcock threw out Raymond Chandler's script and fired him on the verge of going into production. Alma helped adapt Selwyn Jepson's book Man Running for Stage Fright (1950), and co-wrote the script for Suspicion (1941) and Jamaica Inn (1939). On and on it goes - and we know only the tip of the iceberg of Alfred and Alma's professional collaboration.

Right to the end, according to David Freeman who worked with him on that last, never-made, Hitchcock film, Alfred "desperately wanted" Alma's approval.

"Each time he would mention a story point or repeat an exchange of dialogue," Freeman recounts, "he would glance up at her to see if she was smiling. I felt as if I were intruding on someone's first date. At that time they had been married more than 50 years."