He also fought against what he saw as the evils of the star system which afflicted the West End in his day as now. He hated acting which exploited the actor's personality rather than the playwright's character. He struggled hard, and to some extent successfully, to establish in the 1940s and 1950s a group theatre company along the democratic lines of Harold Clurman's famous pre-war American model.
He also defied the two most powerful men in the British theatre, the Lord Chamberlain as censor of plays, and Hugh ("Binkie") Beaumont who controlled the fortunes of the West End theatre and the lives of most people who worked for it.
There is no doubt about it. Cotes had guts; and though he had his setbacks and his principles (are they not bound together?) he survived. There was no keeping him down. If the theatre seemed at one point impregnable he went off and made films (he was the slightly older brother of those film- making twins the Boultings, John and Roy), or directed plays and series for television.
And, if there was nothing else doing or while he was doing that he wrote books on George Robey or Charlie Chaplin (The Little Fellow: the life and work of Charles Spencer Chaplin, with Thelma Niklaus, 1951; George Robey: "the darling of the halls", 1972) or his idea of what the theatre ought to do: in a fiery tome called No Star Nonsense (1949), he attacked practically all the West End stood for.
He had his hits, in the West End and on Broadway; and the one that resonated round the realm was Pick-Up Girl which moved from his cosy club theatre in Notting Hill into the West End as soon as Queen Mary had seen it. Yet it is as The Mousetrap's director that he created theatrical history.
It wasn't that he was remembered strictly for his direction of the play, for the way he orchestrated its original production; not even his flatterers would argue that, though nearly all the first-night notices of 1952 paid tribute to the subtlety and atmosphere, timing and tension of his staging. The tribute paid to him as director ever since the play opened in Newcastle upon Tyne had nothing to do with the art of the theatre. It was his royalties. They constituted a 1.5 per cent share of the takings (which have amounted over the years to well over pounds 25m). This kept him in the public eye.
Since he worked on the show it has required another 20-odd directors to keep it in shape over the years. Cotes was never asked to. Why not? Because he insisted on his royalty rights. He refused the offer of a lump sum which the producer, Peter Saunders, and the leading actor, Richard Attenborough, urged him to accept once the play had started to show signs of immortality.
Was he therefore not one of the luckiest directors of all time? Or just shrewd? He was surely wise to stand his ground, not for the first time, even at the risk of litigation. Indeed Cotes was no stranger to litigation or the lawyer's letter, as many a newspaper editor and dramatic critic, not to mention theatrical person, was made aware.
Cotes deserves, however, to be remembered for more varied, vigorous, courageous and artistically interesting enterprises than the staging of a whodunnit, however long it has run. He was a kind of pathfinder in what are considered by people who did not live through them to have been the darkest days of British theatre, the 1940s and 1950s.
They were ruled not only by the legendarily smooth and ever-smiling Binkie Beaumont, who as Tyrone Guthrie said (though few others dared to) could "make or break the career of almost any worker in the British professional theatre", but also by the stage censor.
Pick-Up Girl was a serious- minded American tale of child abuse and venereal disease. Obviously a licence for public production was out of the question since it had lines like "They were both wearing nothing" and alluded to miscarriages, abortions and syphilis. As luck would have it, though, the Queen Mother, Queen Mary, tottered into Cotes's tiny hall at Notting Hill Gate after reading the rave notices.
For some reason she seemed to think that Somerset Maugham was the author. As she shook hands with the cast afterwards, she inquired of Joan Miller whether their next play would "also" be by Maugham. Sometimes the keenest playgoers can muddle authors. It was in fact by Elsa Shelley. Anyway, Queen Mary's approval brought approval from the censor and the play transferred to the West End, where it filled two of the largest theatres (first the Prince of Wales, then the Casino, now the Prince Edward) before touring. That was one in the eye for stage censorship, which still had 23 years to go.
And Binkie Beaumont? His taste in plays had perhaps given more people more pleasure than any other London manager. Well, Pick-Up Girl had made Cotes fashionable enough for Beaumont to ask him round for tea to discuss what play he would like to direct. They chose Deep are the Roots, a Broadway drama about racial prejudice.
Two days into rehearsal, however, Cotes was fired. No reasons, no apologies. Apparently its leading actor, Gordon Heath, wanted a carbon copy of Elia Kazan's New York staging but Cotes, who had no such instructions, protested forcibly.
Joan Miller, who was in the cast, promptly resigned. She was, however, one of the country's finest actresses, and Beaumont then invited her to "star" - Cotes cringed at the word - in his next West End production as the heroine of Dark Summer (Lyric, Hammersmith, and St Martin's). It was a triumph for her, but illness interrupted the run. She could not be replaced; and that was the end of her career with the mighty H.M.Tennent Ltd.
Had both Coles and Miller (by then married) been blacklisted? Beaumont denied such a list's existence, but Cotes and Miller took a certain pride in being on it and returned to their group theatre ideal at the New Lindsey, Notting Hill, which they practised not only in Pick-Up Girl but in plays by Priestley, Pinero, Strindberg, Ibsen, Clifford Odets and other American playwrights.
Then they moved - as the Peter Cotes Players - for two seasons at the Library Theatre, Manchester, which included transfers to London, and in 1930 founded, again in west London, the New Boltons Theatre Club (it had to be a club to avoid the censor's ban), which they opened with Lillian Hellman's lesbian drama The Children's Hour.
Cotes went periodically into West End management (Hot Summer Night, Girl on the Highway, Staring at the Sun, Janie Jackson, The Old Ladies, Look, No Hands). He also worked in television.
Aside from his books on Chaplin and Robey, he published on the Barbirollis (a collaboration with Harold Atkins), on the circus (with Rupert Croft- Cooke), and two volumes of autobiography; the second, Thinking Aloud, appeared in 1993. He was a criminologist and a familiar name to correspondence editors of the national press, for which (including The Independent) he wrote many a theatrical obituary.
Cotes wasn't exactly born in a trunk but the theatre had been his life ever since, aged four, sitting between his parents Arthur and Rose Boulting, both actors, at the Portsmouth Hippodrome, he had been lifted over the footlights to present a bouquet to Vesta Tilley. With his mother at the piano he went on to entertain in hospital, as an infant, the wounded troops back from the Western Front.
He played the halls in revue, in cabaret, in films and in rep. He directed one of the Arts Council's earliest tours to theatreless zones, including the Welsh coalfield. And as long as he ran his own company under his own management he was happy and successful.
There was, however, something in his temperament which prevented him from being able to ingratiate himself with other managements. Otherwise, surely, he would have obtained the rights of Peter Pan, which he had longed to direct since his boyhood. He toured in it in the 1920s. He had been a Darling child, one of the Lost Boys, Starkey the pirate and Slightly. He loved the play as he loved no other, and it grieved him to see the annual mess which the post-war London theatre made of it.
The leading authority on Peter Pan (see Kenneth Hurren's 1977 book Theatre Inside Out) named Cotes as the best man to stage it. Cotes negotiated. He sensed encouragement. He never gave up. He never got the rights. Why he didn't was as much a mystery as his dismissal from Deep are the Roots had been.
Was Binkie's famous iron fist within the velvet glove still casting some kind of spell over one who had dared to cross his path a quarter of a century earlier? Or was it another enemy? Cotes was not afraid to be himself at all times, but it cost him dear, even if The Mousetrap, which he never went back to see in 40 years, paid off.
Sydney Arthur Rembrandt Boulting (Peter Cotes), actor, producer and director: born Maidenhead, Berkshire 19 March 1912; married 1938 Myfanwy Jones (marriage dissolved), 1948 Joan Miller (died 1988); died Chipping Norton, Oxfordshire 10 November 1998.