Above Suspicion: The Red Dahlia (ITV1, 9pm); Great British Railway Journeys (BBC2, 6.30pm); Generation XXL (C4, 9pm)

LIKE her biggest hit Prime Suspect, Lynda La Plante’s latest TV venture Above Suspicion has a female cop at its heart.

But Anna Travis is, apart from the detective link, not at all like Jane Tennison.

Starring in the latest in a long line of La Plante grim and gritty thrillers – think Trial And Retribution and The Commander as well as Prime Suspect – is Kelly Reilly.

She’s already to be seen on the big screen in Guy Ritchie’s new Sherlock Holmes film as Dr Watson’s fiancee and has High School Musical star Zak Efron among her co-stars in Me And Orson Welles.

She was happy to leave Hollywood behind for the second Above Suspicion thriller The Red Dahlia because Anna fulfills UK viewers’ fondness for characters that are not always perfect.

“Audiences don’t want to be duped, they want to be on the side of the underdog.

I think it’s something we English do better,” says the actress.

“When you watch American TV they all seem to be so flawless. However, the characters from Above Suspicion just look like they’ve not washed in a few days because they’ve been working so hard.”

Detective Constable Anna Travis tackles her most challenging case to date in this new three-parter being shown on consecutive evenings.

The mutilated body of a young woman has been discovered next to the Thames in what looks like an attempt to copy the case of the Black Dahlia, an infamous unsolved murder that shocked Los Angeles in the Forties.

Travis is determined to catch the killer, but her judgement is put to the ultimate test when a journalist comes forward with a set of clues apparently sent by the murderer.

Reilly admits there were days she Tonight’sTV By Steve Pratt email: steve.pratt@nne.co.uk found herself on set thinking “what the hell am I doing? I’m making a film about women who are cut up in bits”. But she adds: “But at the same time I would rather do a piece that looks truthful rather than it all looking lovely and unbelievable.”

Of course, Anna doesn’t spend all her time trailing depraved murderers.

There’s also the growing sexual tension between the DC and her colleague, Detective Chief Inspector James Langton, (Ciaran Hinds) to deal with.

However, it seems we shouldn’t pin our hopes on any flowery love scenes. “It does become obvious that there is something going on between Langton and Travis but it’s not a ‘Mills and Boon romantic gazing’ at each other type of situation, it’s much more complicated,” says Reilly.

IN his new series Great British Railways Journeys, Michael Portillo embarks on four journeys across the length and breadth of the country to see how the railways changed us. The first journey is from Liverpool to Scarborough. In the former city, he meets local author Peter Grant and gets a lesson in how to speak Scouse, as he examines the impact of immigration on the city. He also visits Birkenhead Park, one of the inspirations for Central Park in New York.

AFAST food-obsessed society coupled with sedentary lifestyles means Britons are becoming bigger than ever before. We’re turning into a nation of fatties. But, despite the numerous health warnings, waistlines are getting bigger while life expectancies are getting shorter.

Nearly a quarter of British children are obese or overweight by the time they start primary school. What’s more, that figure will rise to 90 per cent by 2050 if something isn’t done soon.

The two-part documentary Generation XXL follows seven overweight pupils to find out how their size affects them as they grow up, beginning with three youngsters who are becoming aware of their own bodies and the risks associated with their status.