Yet directors and actors liked the sense of theatricality which pervaded his work. There was thought behind it - muddled thought maybe - but it had without doubt a stagy tang amid its Celtic twilit flow and self- conscious flourish.
McLarnon was an Ulsterman and a man of the theatre. He had known that from his youth. Not that he had ever set foot in a playhouse or inherited any theatrical connections. But the stage somehow summoned him when he was being brought up near Belfast, and he went first into the great Sir Frank Benson's company of touring Shakespeareans, then into something even better (for an Irishman), the equally great Anew McMaster's roving troupe, which used to play the fit-ups in Ireland and inspired anybody who spent even the briefest time with them.
Then came a post-war stint for Hugh Hunt at the Bristol Old Vic - still as an actor, though without much success. This is when he began to write plays. McLarnon was a Catholic; Unhallowed was his first title. The Arts Council gave it a prize and the Perth Repertory Theatre acted it. With religious, political, cosmic zeal he went on writing as if he were after the deepest meanings of existence while searching for a theatrical formula.
In 1953, McLarnon wrote a kind of bedroom farce, The Wrestler's Honeymoon, which even reached the Duchess Theatre (as The McRoary Whirl) with a largely Irish cast. It seemed to London playgoers about as tacky as a farce could get.
Yet Laurence Olivier in his managerial heyday had taken it under his wing, before getting cold feet and hiding his link with it. The play's humour existed in a famous wrestler marrying before an important professional bout and attempting not to lose his virility. If the critics were not amused the audience was; but the romp remained a three-day wonder.
McLarnan had a way with words and with stage situations which might leave a critic in the dark if required to dictate an account of it within minutes of curtain fall at the Royal Exchange in Manchester - where most of his stuff was done - but kept one unexpectedly and inexplicably alert, with the lilt and the charge of the language. He had especially the gift for knowing how to seize attention, if not how to satisfy it.
They were surely not bored in Belfast in 1958 when McLarnon's next champion after Laurence Olivier - Sir Tyrone Guthrie - directed, in his exhilarated way, The Bonefire, a lament for Ireland's Catholic-Protestant misery in which, on 12 July of all nights of the year, a Protestant girl and a Catholic sailor try to take their lives together on a bonfire amid the hurly-burly of the Orangemen celebrating the Battle of the Boyne.
The production set Belfast in uproar. Banners of protest were unfurled; marches were provoked. Any transfer of the play to the imminent Edinburgh Festival seemed out of the question. As Guthrie himself cynically observed: "I think it is good thing it has aroused public interest".
But the play made McLarnon a force to reckon with and the critics went on pluckily reckoning with his art for most of the next four decades in such plays as The Saviour (1967), to which the Lord Chamberlain took strong objection until its rude words were removed and the action shifted into a deconsecrated church, set somewhere off the west coast of Ireland in a quarrelsome post-nuclear society; The Trial of Joan of Arc (1969), in which Dilys Hamlett had an emotional ball; and assorted versions of Dostoevsky, Gogol and Sophocles, which extended McLarnon's global influence as a playwright and librettist.
He also wrote for radio. One critic, after a deep evening's listening to one of his half-dozen plays, dithered: "Brilliant or rather silly. I couldn't decide. The programme has enough ludicrous lines to keep one listening."
Gerard McLarnon, playwright: born Clitheroe, Lancashire 16 April 1915; married 1958 Eileen Essell (one son); died London 16 August 1997.