Watch on the Rhine is the curiously misleading title chosen by Lillian Hellman for a wartime family drama that became a film starring Bette Davis. The location is not Europe but America and the show opens with Fanny Farrelly, a member of the New England gentry, arriving in her sumptuous drawing room for breakfast. The character of Fanny is an instant classic. A crashing snob, a bundle of nerves, a lethally bitchy matriarch, she dominates her household by cultivating favourites and crushing enemies with her venomous tongue. And yet her servants treat her with tolerance and affection. To them she seems a tricky but essentially decent oddball who needs careful handling. When they complain about her behaviour, she graciously accepts their chastisement and apologises for overstepping the mark.

This brilliant and complex portrait of a magnificently truculent American dowager feels like an essay in realism rather than a fictional effort. Patricia Hodge delivers a sublime performance. Every time she opens her mouth she unleashes yet another diabolically cutting putdown. She’s like a Shaw character but with less verbosity and more emotional clout.

The plot surrounds the homecoming of Fanny’s daughter, Sara, who has married an anti-Nazi activist, Kurt, in Germany. They smell a rat when they learn that Fanny is entertaining a Romanian émigré, Teck, who sympathises with Hitler and stands to gain a fortune by betraying Kurt. This confrontation provides a surprisingly violent ending to a play that starts as a Chekhovian comedy of manners.

It’s hard to overpraise Ellen McDougall’s superb production. The costumes and sets are exquisite. The small Donmar stage has been arranged to suggest a vast mansion with a playing area barely a few feet deep. The ensemble work is wonderful. Not a dud performance anywhere. The cast includes two juveniles with long speaking parts who perform brilliantly, and Kate Duchêne does a great turn as a crotchety but sweet-natured housekeeper. John Light stands out as Teck, the boo-hiss baddie who tries to blackmail Mark Waschke’s Kurt. And don’t just admire Light’s performance. Ask yourself why he’s not on the Bond shortlist. He’s got the looks, the voice, the polished manners and the air of suave menace. If you seek theatrical perfection, this show comes close.

On The Ropes is an agitprop drama about the Windrush scandal which left a professional boxer, Vernon Vanriel, stranded in Jamaica for years. Though born in the Caribbean, he had the misfortune to be schooled in England where his teachers failed to give him any skills, facts or self-confidence. They told him he was as thick as cement mix and he believed them.

In the 1980s, he was a decent fighter but he blew all his money on girls, crack and cars, and when he found himself destitute in Jamaica, in his mid-fifties, he was helpless. No friend or relative could assist him. He lacked initiative or work experience and hadn’t a clue how to better himself. No support was available from charities or churches, or from the Jamaican state which appears to care little for its native sons. Sleeping rough one night, he overheard a pair of cops plotting to execute him because they regarded tramps as human detritus. This increased his desperation to flee his homeland and return to prosperous, civilised Britain but he was prevented from travelling without a passport even though the authorities knew he had to get to London to apply for one.

After years of vagrancy he finally learned that his case had been raised in parliament. An English court eventually restored his citizenship and awarded him compensation. The script, cowritten by Vanriel, wants to find Britain guilty of racism and cruelty but his personal choices send a different message: if you’re born in Jamaica, clear out, settle in Europe and never go back.

The long first act traces Vanriel’s ascent from classroom dunce to boxing champ. Along the way, he encounters bigotry from promoters, managers and coppers but the effect of these scenes is lost because the cast are all black. Caucasian actors can’t get even get hired to play white supremacists these days. A youngster seeing this show would conclude, reasonably enough, that police forces in Britain during the 1980s were full of black officers. That’s the trouble with colour-blind casting. It erases history.

This overlong show features many of Vanriel’s favourite reggae hits including ‘Kingston Town’ by UB40 which extols the Jamaican capital as ‘the place I long to be’. Really? It’s also the place where psychotic policemen discussed murdering him for being homeless. This production doesn’t quite add up and the excellent cast are wasted on a script that never fully engages us with the central character. Vanriel’s drug problems and his chaotic emotional life are glossed over and he presents himself as an uninspiring victim of lousy schooling, rotten luck and terrible personal choices.