Just as a letter signed by Jewish artists, including Maureen Lipman and Miriam Margolyes, criticises the absence of Jews in UK productions — and one in particular — along comes a play that explores the kind of identity politics the letter seeks to address.

Robert Icke’s latest work is set now but is rooted in Arthur Shnitzler’s 1912 work Professor Bernhardi, about a brilliant, renowned Jewish doctor who refuses a Catholic priest permission to give a dying child patient the last rites. And one of most potent points made by this production is how much pre-Holocaust antisemitism has in common with the post-Holocaust version.

Both are shrouded in attitudes and arguments that might seem reasonable at first glance. Did the doctor’s Jewishness make him insensitive to the needs of a Catholic patient? Yet any objective witness of the incident knows that the decision was clinical, and that the doctor’s ethnicity and religion would never have been raised were he not Jewish.

The same is true of director Icke’s icy, updated adaptation. Set in modern Britain, Juliet Stevenson plays the title role. Her Professor Ruth Wolff is the founding director of a private research hospital on the verge of a dementia cure. Brusque and intimidatingly offhand, Wolff is the best in her field. And when the father — of the dog-collar kind — arrives at the request of the parents to give their dying child absolution, Wolff refuses their priest access to the patient for fear his presence will cause the child unnecessary anxiety. The argument spirals into a superheated conflict between the rational and the religious.

The hospital is drawn into a row involving ethnicity, religion and class. Christian patients need Christian doctors, proclaims a petition calling for an investigation into Wolff’s actions. And in the scene where Wolff appears in front of a hostile TV panel she becomes the target of a familiar modern trend that values identity over ability — this play’s main target.

Despite scenes being driven by a lone drummer on a platform high over the stage, momentum sometimes drags. Yet there is a coup here, and it is delivered by the way in which casting subverts today’s obsession with identity.

Stevenson superbly transmits the fierce, humane intelligence of a doctor whose Jewishness is only relevant because of the way gentiles use it against her. Yet that letter by Lipman and Margolyes et al, which complains of a cultural appropriation by gentile theatre practitioners, suggests there is a view that actors such as Stevenson may be a less than ideal choice for the role of Wolff because they are not Jewish.

It is hard to know where to start with the wrong-headedness of this argument. But you might begin with the letter’s authors using the least convincing of racial sensitivities as a peg on which to hang their complaint of cultural appropriation, and to argue that Jews should play Jews.

Granted, cultural appropriation can be offensive. But unless you are extremely careful you end up saying that jazz can only be played by black musicians.

The letter cites the non-Jewish James McArdle playing the Jewish role of Louis opposite Andrew Garfield’s Prior in Angels in America. Now, you can’t complain about McArdle playing a Jew without complaining about Garfield, who is not gay, playing the gay Prior. In fact someone did.

And the play’s author Tony Kushner said in response, “What am I supposed to do, say to actors ‘Who do you sleep with’ before I give them a role? I mean it’s disgusting.”

Well, exactly. The idea that only Jewish actors can sufficiently understand the Jewish condition to play Jews is a whole bowl of wrong.

Almost as wrong as the idea that only Christian doctors can understand the needs of a Christian patient.