The legend of a woman who disguised herself as a man and climbed to the top of the Church (many scholars – and the Vatican, of course – doubt her existence) is enthralling papal drama handed on a plate, and Brealey neatly handles the escalating tension.

Pope Joan (John to the rest of Rome) is pregnant, apparently with the child of a cardinal called conveniently away by God. And, while her kinship with another cardinal blossoms, the noose tightens around our increasingly-more-obviously-female protagonist.

Piccadilly’s St James’ Church makes for a gorgeous and atmospheric stage here, and director Paul Hart uses the space well, sending his young cast above, behind, to the side and even among the audience throughout the play. The space does, however, have its drawbacks; the grandeur of a church comes with heavy reverb at every word, and the only way for the actors to be heard over it is to SHOUT EVERY LINE. It’s a pity, since there are moments – Joan’s private prayers, for example – that would be far more effective if delivered more quietly.

Also, while the presence of Antony and the Johnsons on the soundtrack seems fitting, the sudden appearance of builders in high-vis jackets only jars. Thankfully, the affront is brief, and we get swallowed back up in the Dark Ages soon enough.

Brealey’s waving of the flag for womankind, while relevant in a country lacking female bishops, oddly limits the play; a little more about Joan’s character would have been welcome. Does she allow the torture of prisoners because she is acting a “man”, or because she is so devout she lacks empathy with non-Papists? Why do we get flashbacks of her brother, if not to explore her psyche?

What Brealey has done well, however, is inject humour into the mix; both she and Robert Willoughby have fun with Cardinal Anastasius, and Joan’s brother garners a few laughs. When Joan tells him she wants to give her soul to Christ, he shoots back with: “What makes you think he wants it?”

With an assured script by one of Britain’s most entertaining feminists and an impassioned young talent in Sophie Crawford as Joan, Pope Joan is a portrait (icon?) of a girl with plenty of power.

Performed at St James’ Church, Piccadilly in London on Tuesday 3 September 2013.