Joan Littlewood, who has died aged 87, was the midwife to Brendan Behan’s success in the British theatre in the 1950s. Her work in bringing The Quare Fellow to the stage in 1956 made the breakthrough for Behan as a playwright and for her as one of the most innovative British directors of the last century.

She devoted her prodigious life in the theatre to a faith she had kept since her Cockney youth. “I really do believe in the community,” she said when old. “I really do believe in the genius in every person. And I’ve heard that greatness come out of them, that great thing which is in people. And that’s not romanticism, d’you see?”

In her struggle to make this conviction flesh through drama (a childhood teacher told her: “You pronounce the word art the way a nun might say the word Jesus”), she was one of the bonniest fighters and intractably cussed personalities the British theatre has known. Although celebrity did not help or console her, she has long been acknowledged, with Peter Brook, whom she despised, as the most galvanising director in mid-20th-century Britain.

Her great causes - community and political theatre, improvisation, working-class language - have passed into the mainstream of drama, and her record remains unsurpassed. The Theatre Royal at Stratford, east London, which was both her temple and fun palace, now thrives on substantial grants and the legacy of her vision. “Good theatre draws the energies out of the place where it is and gives it back as joie de vivre.”

Littlewood was born in Stockwell, south London, to a single mother who frowned on books, but her grandmother, who raised her, was a fine, sometimes bawdy, storyteller. By candlelight, under the bedclothes, Littlewood read library books as soon as she was old enough.

She liked to recall that one of her relatives had rented property in Lambeth to Charlie Chaplin’s family. There was a Chaplinesque solitude and jauntiness about her from childhood on. Only 5 ft 2 in tall, she usually wore a cap or hat half-obscuring an expressive face with an attractive grin. Her first impact on the stage was in comic parts, and she was proud that she had been approached by one of comedian Stan Laurel’s comic scouts.

She excelled as a scholarship girl at convent school. At 12, she asked her grandfather why the General Strike had collapsed after 10 days. “What do you want, red revolution?” he asked. Her answer, then and after, was Yes.

She applied for and won the only London scholarship to the Royal Academy of Dramatic Art. There, with a dawn office-cleaning job to supplement the grant, she won the verse-speaking prize and rehearsed as Ellie in Heartbreak House with George Bernard Shaw himself.

However, disliking the patrician RADA accents, she set off for the US by walking to Liverpool. She got 130 miles on foot to Burton-on-Trent before collapsing. Somebody gave her the fare to Manchester, where she called on a former RADA teacher in the BBC’s northern office, Archie Harding. Headlines about her trip - “Joan of the Hedgerows lived on Turnips” - were her entrée.

Manchester brought her closer to the counterculture she sought: she found it in the BBC, where she worked as a producer, and in the Manchester Guardian; but mostly in small, leftist agitprop groups dedicated to taking drama to the people of the north. Lancashire alone had nine companies.

She met Jimmie Miller, better known later as the folk singer Ewan McColl, who became her husband. He was a virtuoso scenarist, performer, orator, enthusiast and womaniser. He had worked in German agitprop and claimed to know Berthold Brecht.

They founded the Theatre of Action in 1934 and in 1936 Theatre Union. Their first show was an anglicised American agitprop text, John Bullion (1934), at the Round House, Ancoats. It had capitalists, bathing belles, street singers, wounded soldiers and a moving news panel all on stage at once. The Manchester Guardian hailed it as “the nearest thing to Meyerhold the British theatre has” and parts of it resurfaced in the opening scene of Oh What A Lovely War! (1963).

She and McColl made their living by acting and reading for the BBC, but their energy went into the stage. They lived with his parents. Her autobiography, Joan’s Book (1994), records with a flicker of sadness that she got pregnant by him and had an abortion.

Theatre Union saw itself as the vanguard of theory; its productions were influenced by Vsevolod Meyerhold, the Stanislavsky disciple who was the first director of post-revolutionary Soviet drama until Stalin purged him.

Littlewood early discovered the writings about movement of the Expressionist teacher Rudolf Laban; she knew, revered and worked with him. His notation of body language dominated dance education for 40 years and is even used now for management training; she adapted his ideas for the naturalistic preparation of actors. She drew from the lighting work of the Swiss Adolphe Appia, who opened the way for realism in stage design. However, the inspiration to which she returned most often when she spoke was the original 16th-century Italian commedia dell’arte, those travelling troupes of radical players.

The little republic of the company survived hand to mouth through the second World War, often splendidly reviewed but always refused grants by the Council for the Encouragement of Music and the Arts, the Arts Council predecessor. She and McColl were blacklisted by the BBC and by the forces entertainment group ENSA as subversives. By the end of the war, her reputation was such that the BBC asked if it might consult her about features and drama. Instead, she took another step on what she called “the long road to heartbreak”.

In 1945 the group hired a lorry, renamed itself Theatre Workshop and went on tour.

The group had been joined by two teenage communists, Howard Goorney and Gerry Raffles, a public school runaway. They became lifelong recruits, Goorney as a principal actor, Raffles as the backstage linchpin. Littlewood’s relationship with McColl was over and Gerry Raffles, handsome and nine years younger, had, to her amazement, fallen wholeheartedly in love with her: their bond was to last more than 30 years.

In February 1953, Littlewood and Raffles rented the Theatre Royal, Angel Lane, E15, a dilapidated palace of varieties reeking of cat urine. Their first production was Twelfth Night. They followed it with classical seasons including Volpone, The Dutch Courtesan and a reputedly outstanding Richard II from Harry H. Corbett (later in television’s Steptoe And Son).

The production of Volpone represented Britain at the Paris international theatre festival in 1955 and was a huge hit. Success in Paris meant London critics took notice.

Back in London, the breakthrough came in May 1956 with The Quare Fellow, by Brendan Behan, set in prison on the night of a hanging. The company’s exceptional flair for improvisation and rewriting - Behan’s script was chaotic - drew full houses. “We must make them sit up, Brendan,” she told him. “We must entertain them, jolt them out of their slumbers.”

The success of the play, which transferred to the West End, was crucial to both of them. Until then Behan was unknown outside Ireland and Littlewood’s career was at stake. The opening night coincided with a Commons debate on capital punishment and in the audience was Sidney Silverman, the MP leading the campaign to abolish hanging. Also in the audience were a number of Behan’s old IRA friends and, glancing at the stalls, he remarked: “I’d say there’s 200 years of penal servitude in those seats.”

There were more transfers to the West End: Shelagh Delaney’s A Taste of Honey, Behan’s The Hostage, Lionel Bart’s Fings Ain’t Wot They Used T’Be, Wolf Mankowitz’s Make Me An Offer and Stephen Lewis’s Sparrers Can’t Sing. All were uproariously indelicate working-class comedies, although when necessary, as in A Taste of Honey, Littlewood could direct with great delicacy.

They created their own fashion, a reaction to the stultified West End theatre. By comparison, as Behan remarked, John Osborne’s Look Back in Anger was about as angry as Mrs Dale’s Diary, the BBC’s genteel radio serial of the day. During this period Littlewood could do no wrong. She improvised a line in The Hostage - “He died in a foreign land and at home he had no one” - and had the critic Harold Hobson declare it the best of its kind for 2,000 years.

Her methods were legendary. The young Michael Caine lasted only one production. “Piss off to Shaftesbury Avenue. You will only ever be a star,” she told him. The young Richard Harris stayed for five, including Fings.

She had three shows in the West End by 1963, triumph on a Lloyd Webber scale and to incomparably higher standards, but without his managerial back-up. Exhausted and miserable, she walked out at the crowning moment when she and Raffles had managed to buy the theatre.

Her last glory was the peerless Oh, What A Lovely War!, a work of genius in which all her techniques came together. It began as an idea by radio producer Charles Chilton for a project, with the BBC Singers, about the first World War. With Raffles she wrote a mixture of agitprop and pageant play, sacking the singers and giving the tunes to pierrots.

Gerry Raffles died at only 51 on holiday in France, having worked his heart out. Losing him took the guts out of her.

She rented a flat to be near his grave at Vienne, near Lyons, and was befriended by a neighbour, the octogenarian Baron Philippe de Rothschild, who had run a theatre in his youth. She called him Guv. They were matey but, she said, platonic companions until he died in 1988.

She lived on in France, doing a little theatre. In 1994 and 1995 she returned to Britain for the launches of her book. She muttered of defeat, but was always feted. She died in Paris last weekend.