‘Ah, another sheep going to the slaughter,” says schoolmaster Weston. His voice drips with venom as he adds: “Or should I say black sheep?” New, and entirely untrained teacher Ricky has arrived for his first term at a secondary modern school in bomb-blasted Stepney, East London, just after the Second World War. Ricky, a demobbed Spitfire pilot, is a highly skilled engineer, but has been turned down at every job interview because he is black. Weston (Paul Kemp) is a thoroughly obnoxious racial bigot.

To Sir, With Love started life as an autobiographical book by E R Braith-waite, and was then made into a film starring Sidney Poitier. Now it has been adapted into a sharply scripted stage play by Ayub Khan Din, and produced up the A43 at the Royal and Derngate, Northampton. The story follows Ricky into the classroom, where bedlam reigns and there is zero respect for authority.

Intending to start his first lesson with a discussion about Chopin and Keats, Ricky quickly has to lower his sights as he discovers that most of his teenage pupils can barely read at all.

Staff turnover at the school is high, and Ricky’s predecessors have left in quick succession. But Ricky perseveres, encouraged by an inspirational headmaster, who believes that children should be allowed to develop their own opinions, and speak for themselves without getting a clip round the ear in the process.

Headmaster Florian comes over as a patrician but intensely humane character in a superb performance from Matthew Kelly (at all evening performances; Paul Kemp plays the matinées). Kelly leaves you wanting to know much more about a headmaster who is obviously highly experienced but also has views on education that are way ahead of his time.

But the star performance comes from Ansu Kabia as Ricky. You forget that Kabia is an actor playing a part as Ricky gets to grips with lippy, rough-round-the-edges Monica (Harriet Ballard), antagonistic Denham (Mykola Allen) and the rest of the class — most of them enthusiastically played by local actors, who blend seamlessly with the professional cast. Gradually Ricky wins through, although racial tensions remain — a relationship with white colleague Gillian (Peta Cornish) is doomed to failure.

The production is directed with gusto by Mark Babych, and includes some invigorating 1940s music and dance routines. Yes, the happy ending is a little hard for a cynic to swallow, but this is a real feelgood show.

To Sir, With Love