Kings Charles III (Wyndham's Theatre)

What a brave piece of work this is from Mike Bartlett and director Rupert Goold, fully deserving of its must-see status. In an age when the mere idea of a play about monarchy inspires images of sepia-toned banality, they serve up a gripping 'future history' of the Windsors that is nothing short of Shakespearean in scale and operatic in drama.

I've long pitied the position of the Windsor clan – in this day and age to be Royal seems to mean little more than inherited celebrity – and Bartlett paints them as a family riven by duty in the wake of Queen Elizabeth's death (a mention of her reign lasting 70 years puts us in 2022).

Charles, having waited his turn more than any other Prince of Wales in history, is determined to be more than a mere "doormat", and when goaded by a Tory leader of the opposition to refuse to sign a bill restricting freedom of the press, sparks a constitutional crisis that threatens to bring his fate in line with the first King Charles.

Meanwhile, Prince Harry has finally found love with a left-wing art student, and sets off on a journey of discovery that leads to an epiphany in a kebab shop. And the darlings of the column inches, William and Kate, are standing in wait as the crown's last hope, with Bartlett portraying her as a brilliant political tactician masquerading as a mannequin.

At first it feels a little like a live Spitting Image, and the mock-Shakespearean verse takes a while to attune to, but Bartlett cleverly twists the tone from satire to state-of-the-nation drama. And he addresses so many questions regarding not just the institution of monarchy in the 21st century, but wider British identity – so pertinent with the Scottish referendum looming – that it feels like essential viewing to all on this island.

The cast are uniformerly superb, with Tim Piggott-Smith lending a Lear-esque grandeur to the title role, wisely avoiding an imitation of Charles' trademark husky tones and instead suggesting a man hamstrung by his bookish inquisitiveness. Oliver Chris shows William as being much closer in spirit to his grandmother than his father, while Richard Goulding has great fun as the hoodie-sporting Harry, who just wants – shock horror – a job.

Lydia Wilson, though much shorter than the real Kate (she often stands on a step above her husband to compensate), flicks her hair as though a lethal weapon, while Margot Leicester is all-too-believable as the patronising Camilla. There are solid turns too from Adam James as a Blair-like Labour PM, left with no choice but to invoke riots outside Buckingham Palace, and Nicholas Rowe as his slimey opposite number, who plants the seed of Charles' destruction.

And it's all played out at Wyndham's – one of the finest West End playhouses – in designer Tom Scutt's atmospheric brick-lined arena, which invokes all the atmosphere of the Almeida (it's lost nothing in transition) while providing a timeless sense of Royal courts gone by. Mention too must go to Jocelyn Pook's suitably epic compositions, played live from a box by stellar duo Belinda Sykes and Anna-Helena McLean.

This is the play of the year no doubt. Long live King Charles III.