Former London’s Burning star Heather Peace tells about her new Waterloo Road (BBC1, Wednesday) character, ex-military teacher Nikki Boston, who gives the kids their marching orders…

Tell us about your role in Waterloo Road…
“I play Nikki Boston who’s applied for the Head of English job, but she’s been called in for a day’s trial with another candidate to see who’s best for the job.”

Nikki is ex Army and pretty tough, so how do the pupils react to her?
“Nikki is old-fashioned in her teaching methods, but the kids grow to like her. She’s quite cool and trendy, but doesn’t stand for any nonsense. She sets up a cadet course at lunchtime so that anyone in trouble has to go out marching. She’s one of those teachers who can control a classroom because the kids all want her respect.”

What happens when Nikki catches Josh taking drugs?
“She decides to straighten him out they way they would in the Army – a short, sharp shock to sober him up. So she marches him into the changing rooms and holds his head under the shower!”

How does that go down with his dad, Tom, who’s also the Deputy Head?
“Their relationship is very up and down, but there’s definitely an attraction between them.”

You’re keen on fitness and have run marathons, do you think that’s why they picked you for the role?
“Yeah, I’ve always been into my fitness, but I’d just finished filming BBC3’s Lip Service before I started on Waterloo Road. There’s a lot of nudity in that show so that was a good incentive to get down the gym!”

Are you running in this year’s London Marathon?
“No, I’ve run three marathons, but my next challenge is a triathlon in April. I normally do stuff for leukemia research, but the triathlon is just a personal goal. It makes you think, ‘Ok, I’ve got two months, I’d better get working.’ I see it as part of the job as well.”