大象传媒

Guest star: Barbara Flynn plays Lt Colonel Petra Summers (episodes 3 & 4)

There's something very creepy about no-nonsense army doctor Lt Colonel Summers. As chief officer of the military rehabilitation unit it's her duty to treat soldiers who have psychological problems.

But, as the story unravels, it seems she may have a deeper, more sinister motivation.

"I don't know why I get cast in these roles, but feisty strong women is kind of my bag really," says Barbara Flynn of her Sea Of Souls persona.

"From Cracker to The Beiderbecke Affair to A Very Peculiar Practice, that's what I get offered. I don't know what casting directors see in me that they think, 'We need a feisty old bag, let's get Barbara in.'

"But, truth be told, they are much more interesting to play than really wet women.

"I've never played anyone in the army before so this was rather different and nice for me, not least because my father was in the Royal Medical Corps.

"Petra Summers appears to be quite a sinister character and it's difficult to tell if she is brainwashing these soldiers or not. There's a real mystery about this woman and that was great fun to try and get across.

"I won't say much more about the story because it's this sense of unease that's going to keep people glued to their screens."

For Summers the army is the reason for her very existence.

"She is strong because she is part of a collective, she finds power in numbers. I think the army is probably the main thing in her life - the army would be her family. Psychiatry would be her passion," suggests the Hastings born actress.

"I don't know much about the army except that when you join you have to commit wholeheartedly to it. You think as a body, rather than as an individual. And that's what appealed to me about Petra, to try and understand that emotionally detached thought process and how you would approach that mentally."

Cunning, charming and very tough, when Petra Summers meets Monaghan there's a real intellectual contest between them.

Says Barbara: "There's a major battle of the sexes going on there and Summers and Monaghan are definitely in competition with each other.

"There's also the question of responsibility and jurisdiction - they both mark out their patches like dogs marking their territory."

For Barbara, filming north of the border was an experience to remember.

"Working up in Scotland made Sea Of Souls a lovely job. I love the wonderful Celtic humour and I think the jealousies and rivalries between Glasgow and Edinburgh are hysterical," adds Barbara, who has just filmed the courtroom drama Malice Aforethought in Dublin with Nigel Terry.

Next the hard-working actress is about to begin filming a comedy drama with Ben Miller for ITV and in her spare time she likes nothing better than to while away the hours designing jewellery.

She says: "I've been doing it for two years now and I've had three exhibitions - in Cornwall, Gloucestershire and Ireland - so I am very pleased with myself because of that.

"I've always been into jewellery and I think that everyone should have a go if there's something that really fascinates them. And it's a nice sideline should the acting work ever dry up."