Most of us Brits have only ever known one monarch during our lifetime. And it’s easy to assume it’ll stay that way forever, but of course we all know a time will come – probably not too far in the future – when things must change, and a new ruler will come to power. But then what?

King Charles III examines this question in unique and ingenious style, imagining the heir to the throne as he finally steps into the role that he was, quite literally, born to play. But when, within days of his mother’s death, he’s asked by the Prime Minister to put his signature to a controversial bill, Charles begins to realise what being a king actually means. As events spiral out of control, he struggles to balance scheming politicians with the expectations of the public and his own family, whilst remaining true to his own conscience and principles.

Mike Bartlett’s Olivier Award winning play is a fascinating glimpse into a possible not too distant future for our country. Though often light-hearted, poking gentle fun at the figures we all know so well (or think we do, at least), King Charles III is also a powerful political thriller that grips from the start – not least because its outcome could affect all our lives. As Charles discovers that holding power is quite different to waiting for it, black sheep Harry’s out meeting a new girlfriend, who might just make him see life a little differently – while golden boy William’s firmly under the thumb of a shrewd and ambitious Kate.

Robert Powell gives a commanding performance as the tortured, lonely Charles, a man desperate to cling on to what he sees as his God-given birthright, and with all the trappings of authority but none of the power to back it up. Richard Glaves gets some of the biggest laughs as Harry; his awe at the wonder that is Sainsburys is quite delightful, and Glaves’ performance captures all the frustration of a young man tied to an institution in which he has no significant part to play. After some initial misgivings, I also enjoyed Jennifer Bryden as Kate – particularly once she drops the saccharine sweetness and lets her inner Lady Macbeth out to play.

Most of the action takes place within the palace walls (with Harry the only royal to escape and venture into the world outside), and Tom Scutt’s majestic, towering set and Jocelyn Pook’s haunting choral music combine to provide a constant reminder of the weight of history and responsibility bearing down on the new monarch’s shoulders.

King Charles III is not at all what I expected… it’s better. This is a play that’s not just entertaining, but wonderfully inventive and incredibly relevant, raising important questions that could well affect our future in the years to come. For most of us, the monarchy is a decorative institution that exists mostly for our amusement. But it wasn’t always that way – and who’s to say it always will be? Obviously, chances are slim that the play’s an accurate depiction of how the future will play out – but it’s nonetheless a powerful reminder of the fact that, one way or another, the monarchy as most of us have always known it is on the verge of major change. So I guess we’ll just have to wait and see what happens next…

King Charles III is at the Marlowe Theatre, Canterbury, until Saturday 31st October.