AS far as they are concerned, today’s average middle-class liberal type of person lives in a world of certainties.

Brexit? Easy. The EU prevents war and anyone who disagrees is a xenophobic fascist. Left wing? Very good. Right wing? Very bad.

Then there’s ‘positive’ discrimination. Yes, that’s another tick in the box marked political correctness. But is that necessarily a good thing?

Writer Joshua Harmon has created a masterpiece of a play and should be congratulated for having the sheer bravery to confront many of the cosy assumptions and inverted prejudices of the present age.

He tackles the subject of race and ethnicity and its treatment by those in control of educational institutions with alarming honesty.

And Harmon should know. Being Jewish he’s fully aware of the present rising tide of bigotry.

The Masons’ son has just failed to win a place at Yale, having lost out to a black student. Theoretically, the couple should celebrate this victory for diversity. Except they don’t…

Instead, they’re gutted. And true to form, the Masons set about doing their best to have the decision reversed.

This then, is the theme of Harmon’s play. When the virtue-signalling classes are presented with an ideological dilemma, it’s to hell with principles, and self-interest prevails. There are stupendous performances from Alex Kingston and Andrew Woodall as a couple caught in a web of their own orthodoxy, trying to make sense of a situation of their own making.

Meanwhile, friend Ginnie, portrayed with fashionable hysteria by Sarah Hadland, shows just how lifelong friendships can so easily be jettisoned over a single issue. Sounds familiar? But the star of the show is undoubtedly Ben Edelman’s take on academically rejected son Charlie. His spoiled brat rant was a total tour de force that seemed to go on for ages. I never wanted it to end. Admissions will annoy, shatter illusions, and inevitably go right over some people’s heads. It runs until Saturday (June 15).