It’s evident in Bri, whose marriage to Sheila is buckling under the pressure of 10 years of caring for their severely handicapped daughter, Josephine (“Joe”). Nichols gives this couple cathartic soliloquies and asides to the audience as they trade jokes and concoct self-dramatising fantasies to cope with the strain. They know that we know they are hiding behind a performance.

Whereas Owen seemed a little uncomfortable with the comedy, Izzard is in his element when addressing the audience or role-playing past experiences with an incompetent GP, Viennese paediatrician and trendy vicar. At times he can display childish glee for silly pranks, then slide into an almost hippie-like vagueness as if tuning out his pain.

But while Owen came into his own in the less vaudevillian second act, when the couple are visited by smugly do-gooding friend Freddie (John Warnaby), his squeamish wife Pam (Robin Weaver) and Bri’s doting but slyly malicious mother (Prunella Scales), Izzard seems a slightly underpowered presence. Yet he always plays wonderfully with Victoria Hamilton’s Sheila, whose constant anxiety and dogged optimism that her daughter will get better make for a heartbreaking combination.

The supporting characters may spin off into caricature, and Nichols’s deconstructionist theatrical games (Bri’s mother remarks at one point that “I hate a play with language”) can seem dated and arch, but Hamilton provides the emotional anchor for Laurence Boswell’s production. It’s a moving and must-see performance in a play whose blend of unsentimental humour and stress-induced cruelty still has its powerful moments.

How to handle the laughter and the tears is the problem faced by any director of Shakespeare’s rarely performed early history play King John, a tricky mix of bathos and tragedy. For his RSC revival, newly transferred from Stratford to the Barbican Pit, Gregory Doran strips the play of its pageantry — the action takes place on a black wooden stage with only a bleached wooden throne — to emphasise its darkly comic perspective.

This is a deeply cynical look at 13th-century power politics in which John tries to defend his claim to the throne against that of his young nephew, Arthur, who is backed by France and Austria and the blessings of the Roman Catholic Church. Guy Henry’s superb portrayal of this shifty and petulant king — a Richard III with the evil but not the genius — establishes the play’s medieval realm as one where treachery rules and alliances shift.

While Doran highlights the satirical edge with which the play rips open the realpolitik, he still manages to make the tragic fate of Arthur moving. The pain of the dead boy’s mother Constance — played with blazing intensity by Kelly Hunter — spreads like spilled blood across the final two acts. There are other fine performances, including Jo Stone-Fewings as the bastard son of Richard the Lionheart and mocking commentator of the play, and David Collings as the wily papal legate who proves to be the master spin doctor of his day.