Oh sister. What would Jane Tennison say? Prime Suspect's no-nonsense detective superintendent would probably choke on her quadruple vodka, although she's now retired and on the wagon. For in Above Suspicion, ITV1's successor to Prime Suspect, rookie detective DC Anna Travis totters to her first murder crime scene in killer heels, mud splattering her catwalk model legs, and vomiting at the sight of the maggot-ridden corpse. Was it for this that Tennison fought endless battles with her sexist colleagues at the Met? Or is this glamorous creature the product of Tennison hard-fought victories? Is Travis the pretty new face of a sort of post-feminist Prime Suspect?
Lynda La Plante thinks Tennison would be wary of Travis, but ultimately won over – and La Plante should know since both women are her creations. For 15 years, from 1991 until her enforced retirement in 2006, Tennison – inarguably Helen Mirren's greatest television role – won a succession of small victories for women in television's depiction of the police force. We got used to Mirren, the thinking man's sexpot, scrubbed down and unglamorised, scowling at mutilated corpses through cigarette smoke and constantly having to prove her worth to her male colleagues both inferior and superior. La Plante's new girl on the block, DC Anna Travis, gets to keep her feminine charms and intuition as well as be played by leggy redhead Kelly Reilly – an actress of coltish elegance that, unlike Mirren's beauty, is not being disguised.
"As a predatory creature I think Jane Tennison would monitor her very closely because she's very beautiful," La Plante tells me. "But if Travis proved to be an intelligent police officer then I think that would be a plus for her. She'd have bypassed the feminine."
And they don't get a lot more feminine than Kelly Reilly, the 31-year-old actress from Eden Lake, He Kills Coppers, Mrs Henderson Presents and an Olivier-nominated stage actress to boot (and who, by one of those quirks of fate, began her career in an early episode of Prime Suspect). Reilly reckons most of the old battles have been won as far as the police force is concerned. "Institutional sexism is yesterday's news," she declares. "The reality is that there are now many, many brilliant women in the police. I don't know if Anna would have an easier time if she were a guy. Probably not until she shows her worth."
In the two-parter, which begins tomorrow and concludes on Monday, Reilly's Travis is seconded to the hunt for a serial killer of prostitutes. Her new boss is a former colleague of Travis's father, who was a well-regarded Met detective. (Reilly's own father is a retired policeman.) Compared with some of Jane Tennison's former adversaries, especially the hostile DS Bill Otley – memorably played by Tom Bell – DCI Langton is a pussycat.
In the opening half-hour there is much scene-setting as to the current state of sexual politics. DCI Langton (played by Ciaran Hinds) is no paragon of reconstructed masculinity. His female subordinates are still expected to fetch sandwiches (albeit not without backchat), but he is positively benign compared to Tom Bell's scary dinosaur Otley.
"The way Travis deals with discrimination is very different to the way it was portrayed in Prime Suspect," says Lynda La Plante. "She deflates it with humour. Or if someone says something nasty behind her back, she ignores it."
Not that inter-gender relationships in the force are without complication, says La Plante. "I spent a lot of time with real female detective constables and they told me one of the first rules they learn is 'don't touch'. Because if you put your hand on a man's sleeve, he'll think, 'I'm having her'.
"Since creating Jane Tennison I've seen so many prototypes of her – all cop shows seem to have this forceful pushy blonde – but times have moved on and a lot of the women I see are of an age to be the rank that they are. I wanted to put on the screen the naivety of a university graduate in the police force. She has not come through the ranks."
And Anna Travis is based on nobody more than La Plante herself. "She is partly me when I started researching the first Prime Suspect, including the autopsy scene in the first episode where Travis spectacularly faints. Like Travis I lied when the pathologist asked if I'd ever been at an autopsy before. I remember him saying 'there's a lot of gas in here'. It was the biggest, lowest fart you can imagine and the cadaver sat up because of the release of the wind."
Kelly Reilly explains that, compared to Jane Tennison, Travis hasn't "got her layers of skin on". She also realises that she herself will face comparisons with the actress who immortalised Jane Tennison, Dame Helen Mirren. As it happens, Reilly played the younger version of Mirren in the film Last Orders and meeting her as a 17-year-old in Prime Suspect.
"I remember I asked her about going to drama school, and she said to me that she thought that drama school was the worst thing I could do and that I should go off travelling, or go to university and study politics.
"Mirren is somebody who walks to her own beat and I like the fact that she's the most successful she's ever been now she's in her sixties. I love it when women really come into their own when they're older. That's much more interesting." Jane Tennison would raise a glass of vodka to that.
'Above Suspicion' starts tomorrow on ITV1 at 9pm