Law & Order (Channel 5, 10pm); Welcome to Romford (C4, 7.30pm); The Lock Up (BBC3, 8.30pm).

IT’S so long since the Law & Order team first started investigating crime – 1990 to be precise. Look at the formula and you can perhaps understand why it’s broken so many records for longevity across the Atlantic.

The first half of the show examines a crime, the second addresses the legal procedure as sentence is passed. It’s so blissfully simple and it’s blessed by a great cast and scripts.

That may be why there was such widespread mourning last May when, after 20 series, Law & Order came to an end.

However, things are a little brighter in the UK, as not only do we now have our home-grown version of the programme on ITV1, but Channel Five still has plenty of episodes of the genuine article left to get through. Presumably, the US TV executive who wielded the axe thought Law & Order was starting to show its age, but there are no signs of fatigue here as the team tackles another tricky case.

In this instalment – the season 17 opener – Green (Jesse L Martin) and Cassady (Milena Govich) investigate when a cop is killed during a botched robbery, and their inquiries eventually lead them to a paparazzo who may have compromising photos of a celebrity mum and her baby.

The case sparks a debate about tabloid journalism that looks set to overshadow the trial. Can the prosecutors keep everyone’s minds focused on the job in hand and ensure that justice is done, or will they get caught up in the celebrity circus?

There’s a chance that, before too long, it will be impossible to switch on the TV without catching a repeat of at least one Law & Order episode (or its many spinoffs) on some cable channel or other, so it may be as well to give yourself a quick brush-up on the basics and history.

Jerry Orbach (Detective Lennie Briscoe) dominated the show from 1991 until the actor’s death in 2004, and since then, Sam Waterston (Executive ADA Jack McCoy) has been one of the main stars.

ROMFORD, for those not in the know, lies 14.1 miles north east of Charing Cross, has a population of about 36,500, and has been part of Greater London since 1965. It also has a lively nightlife, and it’s that which forms the basis of one-off documentary Welcome To Romford.

It charts a typical Friday night in Romford, as seen through the eyes of the town’s cabbies. The drivers of A1 Taxis certainly enjoy a rather colourful time, thanks to their customers.

Most of them are couples – one set are on their way home after a “wedding on the cheap”, and there’s another who have just met on the internet.

Perhaps most intriguingly, however, is a single passenger – who was found lying in the road.

Using a two-camera, split-screen technique, Welcome to Romford aims to introduce us to a kind of nightlife we may have experienced, but not fully understood the implications of for others.

DESPITE constant concerns about Britain’s crime rate, relatively few of us have had first-hand experience of the inside of a cell. Instead, we get an idea of what it looks like from TV or movies.

Documentary series The Lock Up aims to also give an idea of what it would be like to be locked up in one – and, let’s face it, finding out from the comfort of our own living rooms is far more palatable than actually getting arrested.

Each edition follows officers working in the custody suite of a police station in Hull, East Yorkshire. They deal with about 2,000 young offenders each year and we’ll discover how they feel about being banged up.

The first episode sees Sergeant Jane Biglin encountering a few custody suite regulars, including a prostitute and a heroin-addicted thief.