The new TV detector which can reach into any home

And the myths that sprung up surrounding their supposed powers were also worthy of Hollywood.

But the latest weapon in the battle against licence-fee dodgers is a green torch-like device weighing less than 1lb – and it really does work, with frightening efficiency.

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The hand-held detector linked to a set of headphones beeps if an operating TV is inside a radius of 29ft.

It means licensing officers can now target places previously inaccessible by cumbersome vans, such as homes in very remote areas and individual flats in blocks.

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Kate Fisher, of TV Licensing, said that the new detectors will work alongside existing vans 'to enhance an already effective enforcement operation'.

She added: 'The message is clear. We have the technology to ensure that anyone watching TV without a valid licence can and should expect a visit, wherever they live.

'The vans these days are designed to be discreet, whereas in the old days they were more obvious. There is much more focus on being covert and the hand-held device is a logical extension of that trend.

'We tend to work undercover more than in the past. Any van in the street could be a TV detector van these days. We are definitely catching evaders off their guard.'

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More than 25million of Britain's total of 28million homes do have a licence. But around 1,000 evaders were caught each day last year and 214,000 have already been nabbed in 2007.

And it is estimated that 1.4million viewers are still getting away with not paying the £135.50 colour licence – prompting authorities to develop their new weapon.

It is only within the past 15 years that vans have worked with real effectiveness, helped by on-board computers that can check licence details in seconds. And while older vans had only one way of picking up a signal, modern models have multiple methods.

Unsurprisingly, London had the most cheats last year with 55,287, followed by Glasgow (20,390), Birmingham (10,743), Manchester (9,130) and Liverpool (7,634).

Britain's first detector van hit the streets in 1926 to catch radio listeners without a compulsory ten shilling licence – beginning the culture of a bogeyman figure with all-seeing powers.

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A quarter of a century later television viewers became a target for the first time when the radio and TV licences were merged in 1952.

By 1955, fleets of new Hillman vans with twirling antennae were on the roads – stepping up the game of cat and mouse with viewers who refused to pay up.

The Commer van, Britain's longest-serving TV detector vehicle, went into service in 1968 and heralded the age of putting downright fear into the public.

A classic public information film in 1970 summed up the approach. A bespectacled man in a tweed suit twiddles controls in his van as it crawls along a suburban street.

Suddenly, he exclaims triumphantly: 'Yes, there's a TV set on at No 5. It's in the front room – and they are watching Columbo.' The excitement is palpable. The Commer survived until 1983 and TV Licensing now uses more low-key Volkswagen Transporters.

Excuses officers report hearing on doorsteps have included: 'I don't watch it. It's on for my dog. He watches it, but I'm not paying for him', and, 'That's not a TV you can hear in the background. It's a tape of adverts I play to entertain the children.'