An Actor Prepares.

This is the name of the textbook written by the father of acting technique, Konstantin Stanislavski.

The director who transformed the original production of Chekhov’s The Seagull would go on to mentor Uta Hagen, arguably the most successful acting teacher of the 20th century, who played Nina in a Broadway production the same year as Stanislavski’s death. Her pupils included Jack Lemmon, Al Pacino, Sigourney Weaver, Liza Minnelli and hundreds of others.

Another of Hagen’s pupils at HB Studio was Austin Pendleton, the most successful actor you may never have heard of until now. This Actor Prepared for his upcoming role as King Lear at New York’s The Secret Theatre with a bowl of pasta, a tequila gimlet and glass of Malbec. The midnight snack followed a day where he had taught a three-hour class in the morning, saw a student perform in an off-Broadway musical Kid Victory matinee, and run his lines for a Lear run-through which went past 10pm. All this was on a Sunday.

Pendleton, this month celebrating his 77th birthday, has a career like no other in the American theatre. A new short film Starring Austin Pendleton, made about him by his former pupils at HB Studio, Gene Gallerano and David Holmes, reflects this.

There is a link through Hagen and Stanislawski to Pendleton and actors he has taught or mentored including Ethan Hawke, Natalie Portman and the late Phillip Seymour Hoffman, all of whom appear in the film. The famously overrated Meryl Streep also pays tribute to a man she clearly regards as underrated. He has worked with so many people, says Seymour Hoffman in the film, that he renders the Six Degrees of Separation game (most associated with Kevin Bacon) “kind of ridiculous”.

Pendleton has done close to everything there is to do on screen and stage.

“I started with [acting teachers] Herbert Berghof and his wife Uta Hagen,” Pendleton tells me. “It was around the time Albert Finney was playing the part of Luther (John Osborne play) on Broadway. There’s a moment where he’s the monk and he can’t get the knot untied and that physicality opens you up to the whole performance. We were also told in the same week to see Barbra Streisand in Funny Girl.”

That versatility served Pendleton well, as has the elusiveness of household name status. This relative anonymity does not stretch to within the actual film and theatre business, where he is widely known and loved. This has enabled him to work as a character actor since the ‘60s in films including My Cousin Vinny, Amistad, The Muppet Movie, A Beautiful Mind, Finding Nemo and its sequel Finding Dory.

TV shows range from The Equalizer, Miami Vice, Frasier and The West Wing, to the Damian Lewis/Paul Giamatti series Billions.

On stage, he was hired by Jerome Robbins for the inaugural production of Fiddler in the Roof in 1964, and has worked ever since. As a director recent productions include Stephen Adly Gurguis’ Pulitzer prize winning play, Between Riverside and Crazy, Hamlet with Peter Sarsgaard (about which audience member, one Al Pacino, raved: “The joy! And I’m not even in it”), Detroit at the National Theatre, Sheila Delaney’s A Taste of Honey and NC Hunter’s A Day By The Sea (full disclosure: this featured my sister Polly McKie).

Orson’s Shadow, the play he wrote about Welles’ working relationship with Kenneth Tynan and Laurence Olivier, ran at the Southwark Playhouse in 2015.

He played opposite Streisand in 1972’s What’s Up, Doc and she cast him for her 1996 film, The Mirror Has Two Faces. “If you can’t act opposite her, you have got to hang up your saddle.”

What astounds collaborators is that, despite Pendleton never reaching household name status, hanging up his saddle has never appealed.

“We always wanted to try to understand where his insatiable drive to continue working came from,” explains co-director Gallerano, “we could never figure out what it was exactly. We can grasp at it in the film, and many of his famous peers try to as well, and I think that that is what makes him enigmatic. He might not even know.”

“It amazed me that no one had thought of doing something like this sooner,” adds co-director Holmes.

Pendleton remains as keen as ever to work, hunkering down to be in his right mind to play Lear. “I try and learn my lines, I find that helps. So much of the life of the role is in the language. The more you’re secure in the language, the more stuff just happens.”

Lear is the culmination of a lifelong love of the theatre which began at school where classmates in Warren, Ohio included the founding CEO of Fox News Roger Ailes, until last year arguably the most influential figure in world media.

“My mum was involved in community theatre and Roger was one of her students. During the 1952 campaign, he would get up and deliver this brilliantly argued proposal of why Eisenhower should win. Roger really loved his father and when he died, he took that badly. When he came to New York, he wanted to be in theatre, and hooked up with Kermit Bloomgarden who produced plays by firebrands like Arthur Miller and Lilian Hellman. Kermit called Roger into his office and said ‘I’m dying’ and after that happened, Kermit was looking for a father figure. Then along came Rupert Murdoch.”

Ailes left Fox News, twenty years after he’d become founding CEO in 1996, under a cloud of sexual harassment claims.

“When the scandal hit, I emailed him but the only email I had was his Fox News email so the probability is that he never got it. But I worry about him. I know my mum would be worried about him.”

After being in the spotlight for decades, Ailes has been enjoying a period without work. This has rarely applied to his old classmate, Austin Pendleton.