CHRIS TITLEY goes on patrol with the men who know where you live and what you're watching...

LAST Thursday at 12.43pm a household in Heslington Lane, York, was tuned in to Call My Bluff. How do I know? Because I was watching it with them. Had the resident looked out of the window at that precise moment, they would have noticed a van parked close by.

I was inside, huddled over a computer screen with John Barber and Bill Pattison, two men dedicated to bring TV licence dodgers to justice.

On the computer screen was Sandi Toksvig, no doubt trying to bluff her way to an extra point in BBC1's word game. That picture was being relayed from one of the van's four external aerials, which had intercepted a signal emitted from the Heslington Lane house's telly. If the inhabitant had inexplicably chosen to flip to Family Affairs on Channel 5, our picture would have flipped as well.

But in the few minutes we were there, they remained glued to Call My Bluff. That isn't a criminal offence in itself, although some may wish it was. But if the house in question had not got a television licence, the residents could have been prosecuted and fined £1,000.

The crackdown on TV licence dodgers has caused something of a fuss in York recently. Earlier this month the Evening Press reported a poster blitz, with slogans on the back of buses revealing that: "There are three homes in Etty Avenue YO10 without a television licence". Other posters target Constantine and Barkston Avenues.

Some readers have felt this to be unfair. It tars all the residents in one road with the same brush, correspondents have argued. Others say that it makes no distinction between those households who evade the licence fee and the three per cent who choose not to have a television.

John Barber, TV Licensing communications and community relations manager for the north of England, said the message needed to be hard-hitting to get through to a hard core of licence dodgers.

TV Licensing HQ in Bristol holds a computer database of all 26 million addresses in the UK. Of these, 22 million have paid for a TV licence. Most of the four million that haven't will boast at least one television set.

These are the addresses targeted by the detector van teams. And with some success: between 30 and 35 fee dodgers are caught in York every week.

As you might expect, John's message is uncompromising. Watch telly without the paperwork and you will get caught.

"There are two urban myths about this job," he said as we sit in the back of the detector van. "One is that we don't have the equipment to detect TVs. The second is we send red warning letters out to customers giving them a chance to pay. We don't."

In 99 cases out of 100, people caught without a licence but with any technology that can receive TV pictures - whether it be a standard set, a video recorder or a home computer with a PCTV card - will be taken to court.

And I can vouch that those detector vans do contain some impressive snooping technology. They can detect a TV in use from 30 metres away. That was how we came to be watching Call My Bluff inside a van in Heslington.

Driver Bill Pattison, who covers 1,000 miles a week tracking down dodgers, then writes a record of which channel the person is watching. In a genuine investigation, this information can be used as evidence in any future prosecution.

If you live in a block of flats, or off the beaten track, don't kid yourself you are safe. A hand-held detector points staff to the nearest television in any direction. Later this year an even more sophisticated palm top device will be introduced.

When TV Licensing officials call round, householders often claim they do not possess a television. Sometimes a search warrant is sought. The officials are trained to look for evidence of recently removed televisions; John said it was surprising how often the set had vanished but the remote control was still sitting on the fireplace.

"There isn't a typical evader," he said. "We recently caught three people living on a street in Leeds in homes worth £ million. We catch people in affluent areas as well as non-affluent areas."

Interestingly, however, it is the less affluent areas of Constantine and Etty Avenues which are the subject of the advertising campaign in York. John insisted that these were "picked purely at random in Bristol from streets which have at least two evaders".

TV Licensing enforcers will never top the popularity ratings. While the van was parked down a York side street, two men carrying beer cans slurred abuse in our general direction.

"People say to us, 'You are like traffic wardens'," John said. "But 99.9 per cent of people see the van and don't bother us."

Nonetheless it is a job with slightly sinister overtones. For example, if you are watching Channel 4's Big Brother, big brother could be watching you watching it. How does he justify the invasion of privacy?

"Unfortunately there is no other way of doing it. There is £200 million in lost revenue because of evasion. It clearly isn't fair on the 22 million customers who do pay for their licence."

But John's job is not only to talk about enforcement and court action. "There's a kinder face to TV Licensing," he says.

He was in York to attend a Money Advice Conference at the university. Nowadays those who genuinely struggle to pay the £104 annual fee for a colour set will get a sympathetic hearing.

"For many people on low incomes, the TV licence is not a priority debt," John admitted. "The electricity company will eventually cut off your supply if you don't pay, but we don't confiscate your set."

But viewers do not need to pay the fee in one go. There are a range of ways to pay, from direct debit to the 'cash easy entry' scheme. This allows people on income-related State benefit to pay by 26 weekly instalments of £4. For more information call 08705 763 763.

John also works with Citizens' Advice Bureaux and community groups to ensure that people can watch television and remain within the law. And he is involved in the introduction of hugely discounted licences for those registered blind, and free licences for pensioners over 75. It seems like big brother has developed a softer side to his nature.

I don't have a TV licence because...

...the telly's not for me it's for the dog. He likes watching Rolf Harris

...we don't use it as a telly, only as a table

...the cat was sick down the back of the set and blew it up

...I don't live here

...I thought my wife was dealing with it....

Genuine excuses given to the detectors