Mr. Woodthorpe's most famous part was his first professional job. Director Peter Hall cast the young Cambridge undergraduate after seeing him perform with the Marlowe Society (as King Lear, no less). The project? The original 1955 staging of Beckett's Waiting for Godot, a play Hall admitted he did not understand at the time. Mr. Woodthorpe played Estragon, the more plebeian of the plays two tramps, with a distinctive nasal whine, a fleshy, expressive face and what critic Kenneth Tynan called "compassionate lunacy."

The play moved from the Arts Theater Club in London to the West End. In short time, Mr. Woodthorpe was not only a bankable actor but a part of theatre history. He was 24 at the time.

Five years later, he played his second most famous part, that of the mentally unstable shut-in Aston in Pinter's taut psychological drama The Caretaker. His co-stars were Alan Bates and Donald Pleasence.

In between those two landmarks, he toured with the American acting team of Alfred Lunt and Lynn Fontanne in what would be their swan song, Friedrich Durrenmatt's morality parable The Visit. He played the ineffectual Professor Muller, and journeyed with the production to New York, making his New York debut.

Other roles during this heady period included Good Woman of Setzuan with Peggy Ashcroft, Othello with Paul Robeson, Coriolanus with Laurence Olivier, and the musical Zuleika. In 1962, he was part of the opening season of the Chicester Festival, joining leader Laurence Olivier, Michael Redgrave, Sybil Thorndike, Joan Plowright, John Neville and Rosemary Harris. According to the Times, he alienated Olivier and company with his uncensored critiques and comments, and, as a result, was not invited to join Olivier when the National Theatre opened at the Old Vic. Later roles included Bob Acres in The Rivals, John Vanbrugh's Relapse, Pauline Macaulay's Creeper, Jean Anouilh's Poor Bitos and Toad at Toad Hall, a 1970 triumph at the Royal Shakespeare Company. On Broadway, he had less luck, appearing in the flop 1968 Jules Styne musical Darling for a Day, directing the short-lived 1978 work The Playboy of the Weekend World, and starring in Tom Stoppard's Dogg's Hamlet, Cahoot's Macbeth, which lasted 30 performances in 1979.

Among his productions in the 1970s were A Doll's House with Claire Bloom (1973), The Lower Depths (1972), The Soldier's Fortune (1976) and John Mortimer's Heaven and Hell (1976). One of his final performances, in 1995, was as a camp film producer who frequented the wartime drinking den in Rodney Ackland’s Absolute Hell, with Judi Dench.