“He doesn’t believe in art for art’s sake.”

This is not something you hear too often in the arts world, but it is a concept that I personally have a fondness for. I like a message, a meaning, I like a little more.

As does Bernard Shaw, so I am told by Kathryn O’Reilly, from Islington, who some of you will remember as the barge lady on Call the Midwife.

She is currently starring in a production of one Bernard Shaw’s plays at the Watford Palace Theatre.

“It is an interesting piece. I didn’t know anything about Shaw until I started this play. He wasn’t always a playwright he was a music critic critique and wrote novels.

“He believed theatre has to have a purpose, so to the audience were always made to think. In Arms and The Man he looks at marriage, love and war.

“They’re quite heavy things, but it’s a comedy, there’s conflict within that.”

Kathryn plays Catherine Patkoff, the mother of Raina, a young girl who is madly in love with Sergius, a young officer who is the hero of the hour, leading a daring cavalry charge against impossible odds.

But when Bluntshchli, a battle-hardened professional soldier on the losing side, appears in Raina’s bedroom, will she turn him in or will she collude with the hated enemy, and find there is a great deal more to love and war than she first thought?

“The title comes from the first line of a poem by Virgil. The poem glorifies war and what Shaw is doing is dissembling any romantic ideal or notion about war, because during the time of this play there is a war and Shaw is saying, ‘War isn’t glamorous, it is shambolic and awful’.

“You can’t be naturalistic with it, at all. It is presenting ideas, it is a play about roles.”

Whatever the style, Kathryn is well-equipped,; she has had an abundance of training, including the National Youth Theatre, Anna Scher Theatre, Academy Drama School, RADA skill development through Shakespeare at the Old Vic, – and the list doesn’t stop there.

“I went to the Brit School and did media and drama, and then I set up my own children’s theatre company where I produced and directed shows and ran drama workshops. That was called Mojo, – this was when I had just finished Brit School. Then I went to work in television and I went to the Academy Drama school part time.

“It wasn’t until a bit later that I went to London Academy of Music and Dramatic Arts for three years, doing classical training. I graduated in 2008. So I’ve done a lot, it is a real passion.”

She reflects: “I have experienced different styles of training, which is useful in different ways on different jobs and depending on the director’s’ style.”

As well as a long list of theatre credits, Kathryn has TV titles to add to the mix, including a guest appearance on Call The Midwife.

“I played Daisy Blacker” she tells me. “She was a bargee lady, living and working on barges, salt-of-the-earth, working-class lady with four kids already and pregnant with the next one, but this time it is different.

“The midwives and the nun try to make me have my baby in the hospital, but she doesn’t want to.

“It was really, really fun, and it was a great piece to work on; it is such a prestigious show.”

I ask, as I often do of actors, whether she has a preference between the two,; she tells me: “I don’t have a preference but I’ve definitely done more theatre than TV.

“They both require different approaches and different styles of acting, so they both bring their own challenges. I love them both equally.”

I wondered if Kathryn ever gets nervous, and she tells me that she most certainly does, and she is pretty happy about it.

“If you didn’t have nerves at all then that would be a bit worrying, it is part of the adrenaline. Anyone who loves their job and isn’t nervous at any point, whether it is a presentation and standing in front of people, achieving anything like getting a deal, if there isn’t nerves at all then what does it mean for that person? What is the emotional cost? I’ve got no issue with nerves, I think it’s a good thing.”

When Kathryn isn’t on your screen or on the boards she can be found writing. “I write, I had my first play, called Screwed put on, it had a four-week run at Theatre 503 and it was published by Nick Hern Books which was thrilling.”

Watford Palace Theatre, 20 Clarendon Road, WD17 1JZ, until Sunday, October 22. Details: on 01923 235455