Kenneth Tynan hailed the late Nigel DennisThe Making of Moo, a 1957 satirical play of ideas about the evils of organised Christianity, as the first outright assault on religion on the British stage.

The Royal Court cast included George Devine, Joan Plowright, John Osborne, John Wood and Robert Stephens. Devine, the founder of the English Stage Company, said it was exactly the sort of play he wanted to see in his theatre; it was highly intelligent, funny and blasphemous (but not much cop when it came to the characters).

So Sam Walters’ revival at the Orange Tree is of intense curiosity value, at the very least. It proves to be much more in its witty, high-class dialogue, extraordinary ritualistic second act, and ever-present Shavian application in a discussion on ethics in religious sects and movements.

How come no one has revived the play before? It’s an utter mystery, as is the influence of the river god Ega, who is displaced in a colonial dam-building exercise bringing power and electricity to the natives. The engineer Frederick Compton, genially embodied by Philip York, wishes to replace the god with one of his own; he and little English wifey Elizabeth (played with poignards by Amanda Royle), cook up some hymns and new prayers.

Surrounded by the mooing of cattle and the blood-letting of restless natives, the religion of Moo evolves to such an extent that, two years later, the house boy William (sonorously intoned by Ben Onwukwe) is installed as a new “pope”, visitors are thrashed and served up to vampiric virgins and a pair of visiting lawyers find themselves stretched out and stabbed at vespers.

“Lovers of Moo unite, you have nothing to lose but your brains,” says the new Cromwell of the Cromwell Road, and the third act shows the Cromptons in ga-ga land, buttressed by fawning investors, while their son (Christopher Staines) sets off to start his own religion.

Deftly designed by Tim Meacock, Walters’ production restores an important play, and it’s salutary to remember that when Devine launched the ESC, the big hopes were Dennis (who loathed the religious plays of Graham Greene and T S Eliot) along with Angus Wilson and Ronald Duncan. Was John Osborne a happy accident who may have unfairly overshadowed them? Consider and discuss.