New Tricks (BBC1, 9pm)

SOMETIMES you feel that time is not on the side of the old codger cops who make up UCOS (the Unsolved Crime and Open case), particularly when original member Gerry Standing (Dennis Waterman) is mistaken for a care home resident.

I mean, I know Waterman is walking quite badly at the moment, but there seems to be plenty of life in this old dog, but the scriptwriters do love a little fun at the expense of the elderly boys in blue. There is a serious side, of course, with the team taking on a murder report from 79-year-old Nancy, who is struggling with dementia, but is convinced there is plenty to investigate concerning the disappearance of her police officer husband in 1956. After nearly 60 years this is one case which appears to have one foot in the grave already.

Denis Lawson, who plays Steve McAndrew, confirms that he does struggle to keep a straight face around some of Waterman’s antics.

"There's an underlying humour throughout the series...which is great. I always enjoy the scenes with Dennis Waterman, particularly when we're playing comedy. There's a moment where we actually wake up in bed together after a very heavy night, no idea of where we are but we suddenly realise we're in the same bed. We're definitely trying to assert our masculinity. I love that immediacy on camera with Dennis, he'll just throw some extra lines in, and at times it's so funny you have to try hard to hold it together."

But while Steve may be able to rely on his colleagues for support, it seems it's a different matter when it comes to the retired detective's actual family. And this week, Steve's private and work lives collide, as his son is arrested for buying cannabis.

Lawson says: "There's more contact with my son and ex-wife – played by Julie Graham. At one point my son gets into trouble, so I have to have contact my ex-wife, we have to deal with this problem with our son together. It's quite difficult for both of us as it's still quite bitter and I think our son hopes we'll get back together."

Asked about the continuing popularity of the series he says:"Nobody can quite but their finger on why it's so successful, I think it's a mixture of... things, it keeps an audience very interested, the intricacies of plot, and then amuses them along the way, with these rather offbeat characters.

"It's lovely when the public pass by and they're so thrilled to see you and they love the show... I'd never really experienced that level of response on anything else I've worked on. It was really gratifying and shows the huge impact the series has."

Alex Polizzi: The Fixer (BBC2, 9pm)

ALEX Polizzi travels to Leeming Bar, North Yorkshire, to come to the aid of the Keebles, the family behind Heck brand sausages. These former farmers are reliant on the supermarkets to survive, but it's a business relationship that has sometimes left them feeling like the retailers have all the power.

By going behind-the-scenes in a food development kitchen of one of Britain's biggest supermarkets, and learning more about the art of shelf layout, Alex hopes to come up with some practical ways to help the Keebles achieve their goal of becoming the UK's premium banger brand.

Cops and Robbers (Channel 4, 9pm)

IT'S a shocking statistic, but more than a third of crime in Britain is committed by serial offenders – there are now more than 100,000 criminals with more than 15 convictions to their name. Rehabilitating 'career criminals' is the question haunting this new series, which, as the title suggests, meets some of the offenders, as well as the police who are trying to deal with them.