Robert Icke is a clever-clogs, a smarty-pants, a boffin. His Stakhanovite work ethic has established him as the wunderkind of London theatre, churning out his self-penned adaptations of classics from Aeschylus to Orwell in his own pointedly intelligent style.

Now he comes to Friedrich Schiller’s 1800 tragedy about Elizabeth I and her execution of cousin and rival, Mary Queen of Scots, with another very clever device: the actors playing the two queens (Lia Williams and Juliet Stevenson) flip a coin every night to decide who plays which part. The two queens, you see, are mirror images of one another. It’s a clever idea, but along with the dramatic incidental music by Laura Marling and the spectacular symbolic stage-pictures, it all seems a bit on the nose.

I always feel watching Icke’s work that I’m looking at the brightest undergraduate in the seminar showing off. That’s not to say a lot of very impressive work isn’t achieved. Mary (Williams on the night I saw it), locked in her castle awaiting death, projects the watchful stillness of the self-conscious martyr mixed with the occasional deployment of the sexual power and political intellect that got her to her position. Elizabeth (per Stevenson) matches her as the kind of power-dressed sovereign that, in our guilty dreams, might wish ran the country – ruthless, cogitating and imperious, but with her humanity intact. In the sole scene the two share, it is fascinating to watch any attempt to broker a truce quickly collapse due to the dominating personalities of both; while this might have the potential to devolve into the sexist trope of over-emotional women jealous of each other, it seemed to me that both were simply too talented at the game to tolerate the other.

Indeed, Icke is on his best form when he’s busting the Bechdel test with his star performers. Outside of this, Mary Stuart can threaten to fall into melodrama. Rudi Dharmalingam’s Mortimer, who as a young pro-Mary religious fanatic makes certain key links to the present day, is a disappointingly callow performance when the stakes are so high; and it doesn’t help that Icke’s dialogue, while losing the portentousness of much Romantic drama, still sounds like a lot of Ickes talking to each other rather than fully fleshed out characters.

Schiller, indeed, isn’t Shakespeare, and his Hegelian-style tragedy of immovable object and unstoppable force has an awful lot of heavy lifting to do to get the plot out the way (this show is over three hours long, although to Icke’s credit he makes it feel like less). The themes to do with rational legal proceedings are weighty (the revolutionary time of its writing compares nicely to today when employing rational argument against power is notably tough) but I felt distracted from the momentum of the drama.

The politics of the piece get some good laughs: “a majority doesn’t prove a thing is right” is always going to prompt a chuckle in an Islington theatre in 2016. Elizabeth’s understanding of political presentation is rather modern: “what things seem are what they are”, she says, and in a world where people expect certain extra things of a female ruler, that is going to be what she must provide. There’s all kinds to mull over in a UK with a female Prime Minister no doubt, and this is an intellectually stimulating evening of theatre. I’m not sure it’s as great a piece of theatre as its presentation might suggest, but it is certainly worth your time.

Mary Stuart is playing at the Almeida Theatre Theatre until 21 January. Tickets can be bought here.

Photo by Miles Aldridge