Whether or not her character, Rachel, is guilty of murder, the part marks a departure for Burton, whom we associate with tough-but-sensitive do- gooders in hit series such as Peak Practice and Silent Witness. That is not to say, however, that she has shirked challenging roles. In Lucy Gannon's drama The Gift, she was heartbreakingly yet unmawkishly convincing as a mother dying of cancer. She also managed the near-impossible, by making an accountant (Heather Haversham in Brookside) both interesting and sexy. Since her Brookside days, Burton has become, according to one admiring television executive, one of the very few actors whose involvement is enough to "green-light" a project.
Burton is 42, slight and almost disconcertingly serene. She has twinkly eyes and dancing eyebrows, and speaks with a soft Northern Irish accent, which on television she carries from character to character. Her heritage is important to her, even though she remains confused by it.
"I was born into a Protestant family, but I was always drawn to Catholic culture," she says. "As a girl, I was very much into Irish music and literature, and at school I helped to instigate a lot of inter-denominational activity, debating societies and things, but I never felt particularly accepted by either the Protestant or the Catholic community. Also, my mother was English, from Manchester, and had come with no agenda to live in Ireland."
Burton grew up in a village near the Donegal border, where her father was a headmaster. She has fond memories of her early childhood, but then came the Troubles, which more or less coincided with the onset of puberty - double trouble, if you like. This was significant, because Burton's social life was nipped in the bud at an impressionable age.
"I remember people wearing their religion on their foreheads like a number, that feeling of knowing from the silence that you shouldn't be in a particular pub; and I remember drunken soldiers roaming the streets at eight in the morning. Partly as a result of all that, I came out of Ireland rather shy. I certainly didn't burst out of Ireland."
In 1975 she embarked on a drama course at Manchester Polytechnic - "it was the nearest place I could find to Ireland" - and then, following an improbable television debut on The Rod Hull and Emu Show, got the job on Brookside. She grew close to her colleague Sue Johnston, who is godmother to one of Burton's two daughters by the photographer Sven Arnstein. "Suddenly," she recalls, "I had a sense of belonging. Brookside really was like a family. And it gave me so much confidence."
Ironically, that new-found confidence drove her to leave the programme after four years. Unlike many soap stars, she managed to reinvent herself, as Dr Beth Glover in Peak Practice. Amid unsubstantiated rumours of an affair with her co-star Kevin Whately, she then left Peak Practice, but quickly re-appeared on our screens as a pathologist in Silent Witness. This too was a hit, placing Burton with David Jason and Nick Berry on an exclusive list of actors who carry huge ratings with them wherever they go.
Burton enjoyed Silent Witness, but paid a heavy price emotionally. "I had such disturbing dreams," she says. "I kept waking in the middle of the night with thoughts of performing an autopsy. It was awful, but I've got rid of it now."
Characteristically, she has refused to pledge herself to Silent Witness, and intends to keep looking for fresh challenges. "I suppose I'm an old Proddie at heart," she says. "I really believe in the work ethic, that if you work hard it makes a difference, and that if you are doing well, you have to work even harder."
Professionally, one of her keenest ambitions is to play a real person - "a pioneer such as Amelia Earhart, or someone otherwise instrumental in great change". She also has plans to produce a drama about medieval women who were forced by the conventions of the time to write anonymously. "I find suppression very interesting," she says.
On a personal level, too, she knows exactly what she wants. "My parents moved to Cheshire and my children have never been to Ireland. I'm desperate to see my daughter playing the violin in a small Irish village pub." If there is silence as she plays, Burton hopes that, this time, it will be silence of the right sort.
`Forgotten' concludes tonight at 9pm on ITVReuse content