ONE review of Shakespeare's Rose Theatre's Henry V ended with a very short question: Why?

Why had director Gemma Fairlie cast Maggie Bain as King Harry for this summer's production at the castle car park, York?

It is worth repeating Gemma's reasoning: "We auditioned a huge range of actors of all genders for this role, but no-one quite captured the complexity of the character like Maggie," she said.

"Henry is such an iconic figure for the English, he is sometimes more myth than man. But we have to understand why thousands followed him into battle, while also seeing the weight of that responsibility for the nation on his shoulders.

"Henry has a wit, a charm and a charisma that is infectious, and Maggie has that in spades. I know that the audience will fall in love with Henry through her, while hopefully questioning how constructed the public persona of a King is by seeing a woman play a man." So, why not, in other words.

"What we're looking to do is tell the story and gender is not part of that," says Maggie. "We've worked with a fantastic movement and fight director, Jonathan [Holby]who's been in the Army and has been instrumental in talking about the physicality of the play, especially the army scenes.

"There's no one way of playing the masculinity of Henry; there are as many ways of doing that as there are men and women, but my job is to understand what it is to be in Henry's army and to be head of the army."

Maggie's rule of thumb is a familiar one among actors: "As always, you have to play for the truth," says the Black Mirror star. "You have to think about what you're asking them to do as their leader, to do the impossible for Henry, for their country.

"It would be easy to be caught up in all that, to be intimidated by having to say those speeches, but when you're lucky enough to be part of a fantastic ensemble, and I'm saying these lines to these incredible actors, all I can think about is being as truthful to them as they are to me. My journey and my delivery of those lines is just as much affected by they do as I do."

Maggie was cast only two weeks before the Lunchbox Theatrical Productions casts gathered for rehearsals in a specially assembled tented village at York Designer Outlet. "We had one meeting before we began, and Gemma had a very clear vision of the play, but she also said 'Henry is yours to do what you want with'," she says.

"She's incredibly clear in her directing but she also asked our opinions in rehearsal so that the piece makes utter sense, while also working out how to play it in this gigantic space, so throughout it's felt like we've found this play together, which is a brilliant way to do it."

All the Shakespeare's Rose Theatre actors appear in two plays, each peopled by the same set of performers. In Maggie's case, she plays Antonia, the usurping Duchess of Milan, in Philip Franks's production of The Tempest. "I read for a few different things with the casting director, such as Ariel, the spirit, in The Tempest, but not Antonio," she says.

You read that right. Whereas Maggie's Henry V is a woman playing a man, Antonio has been transformed into Antonia. "With so many actors in each ensemble, it's difficult to cast each play, but they've done it so well and the casting director has done an amazing job with everyone thrilled to be part of it.

"And luckily for me, as I have so much to do in Henry V, I get a lot of time in The Tempest to sit at the side."

What does she make of Antonio becoming Antonia? "You're now looking at a brother-sister dynamic with Sebastian, rather than brother-brother, and that gives their scenes together a different resonance," says Maggie.

The Glaswegian actress is enjoying her pop-up Shakespearean theatre season in York. "As a company, we're having the best time, discovering the best restaurants and just generally having a lovely time," she says. "It's a very easy city to slip into."

Shakespeare's Rose Theatre, York, runs until September 1. Box office: 0844 847 2483 or 01904 623568 or at shakespearesrosetheatre.com.

Charles Hutchinson