He was primarily a stage actor, and appeared in a wide range of roles from Shakespeare to farce, modern drama, musicals, drawing-room comedy, and thrillers.

He made some cinema films, particularly in the late 1940s and the 1950s, including My Brother Jonathan, The Glass Mountain, Angels One Five and the 1952 adaptation of the Oscar Wilde play The Importance of Being Earnest.

[5] After graduating with a second-class degree in French and German in 1937 Denison went to the Webber Douglas Academy of Dramatic Art, where he met Dulcie Gray, a fellow student, who became his wife and his frequent acting partner.

[6] He remained with the company until March 1939, playing a range of roles, including Gordon Whitehouse in a revival of Priestley's Dangerous Corner, Redpenny in The Doctor's Dilemma and the Rev Alexander Mill in Candida.

The Stage, in an obituary of Denison, observed that the couple appeared in more than 100 West End shows "and their marriage, which lasted very nearly 60 years, was regarded as one of the happiest in showbusiness".

[9][10] The couple appeared there together in plays including Coward's Hay Fever[11] and The Young Idea,[12] Shaw's Arms and the Man,[13] Priestley's Dangerous Corner[14] and Gerald Savory's George and Margaret.

[15] Denison and Gray returned to London in October 1939; he appeared again at the Westminster as Peter Horlett in Priestley's Music at Night and Stephen Undershaft in Shaw's Major Barbara.

[2] He toured with Roger Livesey and Ursula Jeans in Priestley's latest play, Ever Since Paradise,[16] and had supporting roles in two films: Hungry Hill (1947) and The Blind Goddess (1948).

[19] After a seven-week pre-London tour, beginning in August 1950, Denison and Gray opened at the Ambassadors Theatre as Michael and Agnes in The Fourposter, a two-hander, charting the married life of a couple.

[20] For the cinema they starred in The Franchise Affair (1951),[21] and after a cameo as a reporter in The Magic Box (1951),[22] Denison had a major role in a war film, Angels One Five.

[23] In 1950 Associated British Productions (ABP) had acquired the film rights to The Importance of Being Earnest, and chose Denison and Gray to play Algernon Moncrieff and Gwendolen Fairfax.

"[25] ABP released the filming rights to the Rank Organisation in 1951; the director, Anthony Asquith, retained Denison but cast Joan Greenwood instead of Gray as Gwendolen.

[26] In a survey of productions of Wilde Robert Tanitch describes Denison's performance in Asquith's 1952 film as "a conceited and debonair Algernon, tossing off the epigrams in a bumptious manner".

The company that season included Laurence Olivier, Vivien Leigh and Anthony Quayle, and Gielgud and Peter Brook were among the directors;[31] Denison appeared as Sir Andrew Aguecheek in Twelfth Night, Bertram in All's Well That Ends Well, Dr Caius in The Merry Wives of Windsor, and Lucius in Titus Andronicus.

[33] In 1958 he toured with Gray in a two-hander thriller, Double Cross, but his schedule for Boyd QC prevented him from appearing in the piece when it opened in the West End, and his role was taken by Terence Morgan.

[34] Denison's last stage role of the 1950s was the Duke of Hampshire, with Gray as the Duchess, in a revival of Frederick Lonsdale's Let Them Eat Cake at the Cambridge Theatre in May, 1959.

[9] Back in England Denison and Gray starred in the opening production of the Ashcroft Theatre, Croydon, The Royal Gambit, a play about Henry VIII and his wives, in November 1962.

[44] Gray and Denison appeared in a comedy, The Sack Race, in 1974,[41] and later that year he played Mr Darling and Captain Hook in the 70th-anniversary production of Peter Pan, as he had long wanted to but other commitments had not until then allowed.

[46] At the Old Vic in 1978 he played what The Stage called "an amusingly mouth-pursing, bewildered Mayor" in a revival of The Lady's Not for Burning, and appeared in the same season in Twelfth Night, as Malvolio, and in Ivanov as Lebedev.

In the West End they appeared in Ronald Millar's A Coat of Varnish, and Shaw's Captain Brassbound's Conversion (1982); The School for Scandal (1982 and 1983) as Sir Oliver Surface and Lady Sneerwell; and Fry's Ring Round the Moon (1985 and 1988).

[48] They again appeared together in a tour of Bedroom Farce in 1992, and in the same year began a long association with Peter Hall's production of An Ideal Husband, this time in the roles of Lord Caversham and Lady Markby.

[50] His last appearances on stage were with his wife in March and April 1998 in Curtain Up – An Evening with Michael Denison and Dulcie Gray at the Jermyn Street Theatre.

[41] Denison was decorated by Queen Elizabeth II with the Silver Jubilee Medal in 1977 and both he and his wife were appointed Commanders of the Order of the British Empire (CBE) in 1983.