There is a moment in this, bubbly to the point of fizzing, revival of Richard Rodgers and Oscar Hammerstein’s 1943 musical that recalls one of musical theatre’s great milestones. In this rip-roaring unabashed love letter to the Wild West, with its cowboys and hoedowns, and guns and coy flirting, that moment arrives when farmhand Jud Fry sings about the loneliness of his existence, and the unrequited love he feels for the show’s farm girl heroine Laurey, who the much more eligible Curly is destined to win.

Jud always did strike an unexpected note of social realism in this musical, brimful as it is of feel-good songs such as The Surrey With the Fringe on Top, in which cowboy Curly describes the classy mode of transport he envisages using to take Laurey to a dance.

And then there is cowgirl Ado Annie’s number, in which she declares herself to have what convention would assume to be a cowboy’s libido for members of the opposite sex — or, as she puts it, I Can’t Say No.

It is a song that has never sounded the same for me since Polly sang it in Fawlty Towers to distract dinner guests while Basil rushed out for a takeaway and then used a tree branch to thrash his car after it broke down in a rainy Torquay street.

But back to Oklahoma, 1907, and the upbeat notes struck by its score: there is surely no more optimistic song in the canon than Oh What a Beautiful Mornin’, the composition that establishes the feel-good default setting of this show. So when Jud sings Lonely Room, about living in a shack where he dreams about Laurey, and of her long hair falling across his face, only to wake and find it’s all “a pack of lies”, the number arrives as a massive reality check about how there is room in this feel-good to feel murderously bad.

But what adds to the sense of injustice in Jeremy Sams’s production is that Jud (played by Emmanuel Kojo) is black and so is Laurey (played by the excellent Amara Okereke). So this being a period and place where slavery was still the freshest of memories, when the superb Kojo sings about Jud’s internal life and the sense that he has been unjustly treated all his life, it is no exaggeration to say that he summons something of Paul Robeson singing Ol’ Man River from Hammerstein’s earlier work Show Boat.

Kojo alone is worth the price of a ticket. But there are many other standout performances, too. Josie Lawrence is on the best form I’ve seen as the wise, trigger-happy Aunt Eller and Hyoie O’Grady as Curly has an irresistible swagger about him. Meanwhile Bronté Barbé is also terrific as Ado Annie and in this superbly choreographed evening Isaac Gryn’s dancing has the snap and accuracy that could fit right in to the 1955 Hollywood version.

Granted, the reasons this groundbreaking show caused such a stir —the way songs rise organically out of the plot — have long gone. Nostalgia is the currency here. But a richer, more rewarding evening will be hard to come by.