Based upon his own experience of supply teaching in tough secondary schools, he wrote the controversial 1954 anti-corporal punishment novel Spare the Rod, which was later released as a film.
Despite taking part in daylight bombing raids over occupied France, however, he apparently lacked the manual dexterity demanded in flying, and he was offered the option of a discharge.
There followed a period in which he tried various casual jobs – as a repertory actor in Lancashire, an ARP fire guard messenger, a credit salesman and even a lumberjack – but he returned to the services in 1943, this time with the Royal Navy.
Because of the backlog caused by the war it was a remarkably talented and relatively mature intake at university, and he counted among his friends there such people as Kenneth Tynan, Chris Chataway and Lindsay Anderson (all at Magdalen), Ludovic Kennedy (Christ Church), Robin Day (St. Edmund Hall), and John Schlesinger (Balliol).
W. A. Darlington of The Daily Telegraph was enthusiastic, as was an anonymous correspondent of The Times who, writing of the last of these in December 1955, wrote: "...it would be hard to imagine a finer presentation of Shakespeare on a school stage" and "the man responsible was Mr Michael Croft.
[16] Upset that such an enjoyable experience would no longer be available to them, a group of Alleyn's boys – some of whom were still at the school, some also leaving that year, and some who had already left by then – asked him if it might be possible for them to reunite over the summer holidays to put on a Shakespeare play of their own.
Even more vaguely, I hoped that the Youth Theatre, as I was already calling it in my mind, would develop a real sense of community by bringing together young people from diverse backgrounds to work in a group where even the humblest mattered.
He therefore used his familiarity with the acting of the boys at another local school, Dulwich College – where he had attended plays and adjudicated their "house drama competition" – to invite a few non-Alleyn's pupils to take part.
[18] With another teacher from Alleyn's, Kenneth Spring, as its Production Manager, the Youth Theatre's first play, Henry V, appeared at the Toynbee Hall in the East End of London for the week beginning 10 September 1956.
A Gala Matinée at the end of the week was attended by Peter Ustinov, Alec Guinness, Flora Robson, Sam Wanamaker, Alan Badel, and many of his old acquaintances from Oxford.
[19] The reviews were very positive, but the sponsorship by the Telegraph was for the single production only, and any plans for a permanent and possibly expanding Youth Theatre would depend upon Croft's ability to find continuing financial support.
The King George's Jubilee Trust, which was run by two fiery old generals with no known interest in the arts, and could have easily regarded the Youth Theatre as yet another 'arty' or hare-brained venture, came up with a grant of £500 a year.
[22] The years immediately following Henry V saw other productions of Shakespeare, such as Troilus and Cressida (at the Edinburgh Festival), Hamlet (in London and on tour), and Antony and Cleopatra (at the Old Vic).
The latter was to put on some 6 or 7 plays a year, mainly for younger audiences, early ventures including Vanessa Redgrave in Twelfth Night (1971), Mia Farrow in Mary Rose (1972) and Susan Hampshire in The Taming of the Shrew (1974).
[33] There is hardly a play at the National Theatre or by the Royal Shakespeare Company, or a British film or television series that does not contain someone whom he has influenced, directly or indirectly.
[34] The list of famous actors who started out with the National Youth Theatre includes Orlando Bloom, Daniel Craig, Kenneth Cranham, Timothy Dalton, Daniel Day-Lewis, Sir Derek Jacobi, Martin Jarvis, Sir Ben Kingsley, Dame Helen Mirren, Diana Quick, Matt Smith, Timothy Spall, David Suchet, Catherine Tate, Simon Ward, and Michael York, among others.