THE RED Sierra swings out of the security gate at Edward Road police station at 9.45 pm on a damp Thursday night in Balsall Heath, Birmingham. At the wheel is PC Terry Webb; in the passenger seat PC Jayne McCarthy. They are off to chat up the Brass.

In London and Manchester, the police call prostitutes Toms. In other areas, they are Tarts. In Brum they are Brasses, and Balsall Heath, where most of them ply their trade, has the dubious distinction of being Britain's most notorious red light area.

PC Webb and PC McCarthy are in the vice squad, a team of eight constables (two of them women) and one sergeant who go out day and night to hassle the girls, the men who live off them, the punters - and the sightseers who drive around the area.

On the corner of Park Road two girls are sharing an umbrella. Jayne calls to them: 'Tracey, come here.' One of the girls totters over in her high heels and micro-skirt. 'How are you doing?' asks the policewoman. Tracey replies: 'So, so. It's pretty quiet. I've had one, that's all.' 'Where's Chrissie tonight?' 'I haven't seen her.' 'She ran off when I called her the other night. When you see her, tell her if she ever does that again I'll leg it after her, OK? Right, you've got half an hour. If you're here when I come back, I'll nick you.'

In Strensham Street is a cluster of three girls. Again PC McCarthy winds her window down. 'Come here, sweetie. Oh, it's you Jasmine. How many punters have you had?' The pretty, plump Asian girl says none. As we glide away, PC McCarthy tells me that Jasmine is in high demand, especially among wealthy Asians, and can command up to pounds 250 a time. When we pass the same spot 15 minutes later, Jasmine is missing. 'She'll be with a client in a car park,' PC McCarthy says.

There are two girls on the corner of Constance Road. The officers recognise one, but not the other. PC McCarthy asks for her name and address. Then PC Webb steps in. 'Listen, you pair. We've had a lot of complaints from residents in this road. Go somewhere else - now. If you're here when we come back, you're nicked.'

Nobody is sure just how many KCPs (Known Common Prostitutes) operate in Balsall Heath, although the vice squad officers know most of them. Last year 152 girls were convicted. When part-timers and girls operating on the fringe of the area are taken into account, the real figure could be double that number.

Most of them are street girls, hanging around corners waiting to be picked up by drivers. They charge around pounds 15 for straight sex in the back of a car, pounds 20 for oral. But Balsall Heath has a feature unique to Britain's vice areas - the girls who sit in windows, Amsterdam-style, wearing scanty underwear or basques. They sit there, often baring a breast, and signal with their hands - 10, 15, 20 - to advertise their charges.

The window girls are the main attraction for the cars that stream into the area between 9pm and 3am. 'Look at 'em,' says PC Webb. Even on a wet Thursday, traffic is heavy. 'They've just come to gawp. They come from all over the Midlands and drive round and round for hours, sometimes causing traffic jams. You even get families coming out, bringing young children.'

Occasionally the police have a blitz on the tourist kerb-crawlers, and will stop a car and ask the driver to explain why he is in the area. The excuses they come up with are quite amazing. One said he is looking for a bottle bank. Needless to say, he did not have any empty bottles in his car.

It is this non-stop traffic that produces most complaints. Chief Inspector Barrie Simpson, the man in charge of the squad, says: 'The vast majority of people living here are respectable citizens. Think what it's like for them. We have to try to improve the quality of their lives.'

A number of remedies have been tried to ease a problem the police realise they can never solve. One has been to make culs-de-sac out of the most notorious roads to stop cars circling round. But it has not worked. The sightseers simply drive along streets such as Cheddar Road, turn round at the end and drive back.

A suggestion has been put forward that prostitutes should be moved wholesale out of Balsall Heath and allowed to work in a specially created 'tolerance zone' on an industrial estate where there are no families to upset. But the police doubt whether this would work.

The policy of the vice squad is to try to contain prostitution, to stop it growing or spreading. The officers are told to concentrate on hassling girls in a particular street, or badger punters. 'It's the complaints and feedback we get from the public that direct the way we operate,' says Chief Inspector Simpson.

Back on the streets, PC Webb continues cruising around. The Sierra is his own car; the vice squad's white vehicle - with the registration letters SUK - is too well known.

PC McCarthy winds her window down and calls over to Jane, an attractive 25-year-old in red pants. She compliments her on her leather jacket: 'That's nice.' Jane pulls out a sheaf of photographs of her in other smart clothes. 'You look lovely.'

Afterwards she says: 'You've got to build up a rapport with the girls, even though some nights you have to nick them. They know we're only doing our job, but if we're nice to them they can give us useful information. One of the things they tell us about is newcomers to the streets, some of the ones who are really young, so that we can stop them before they get started.'

Back in Cheddar Road, we're keeping watch on Joanna, dressed in white bra and pants and white stockings and suspenders - her working gear. She's in her mid-thirties, has a pale face, with long dark hair, and is sitting under the glow of a red-tinted light. Of the 61 houses in the road, 12 are used by prostitutes. With bay windows adjoining the pavement, they are perfectly designed for the vice trade. The girls rent the downstairs front rooms for an average pounds 50 a session - afternoon, early evening or late.

A young man in jeans and a blue sweater approaches Joanna's window. After a brief conversation, she opens the door and he goes inside. PC Webb looks at his watch. 'We'll give him two-and-a-half minutes,' he says. 'That's how long it will take to negotiate the fee, get his trousers down and get started. If we catch them on the job, they can't argue.'

After the seconds have ticked by, he hammers on the window. 'Open up, Joanna.' A female voice asks: 'Who is it?' 'It's the vice. Come on. Open up now.' 'Oh hell. Just a minute.'

The door is unlocked and we go inside. The man is sitting on the bed, his head in his hands. He has pulled his jeans on. PC Webb says to him: 'You've come here for sexual services. We saw you soliciting on the street. You have committed an offence and you'll be reported.'

The man gives his name as Paul and says: 'I only came in for a chat.' Terry says: 'These girls haven't got time to chat. Anyway, you don't need to take your shoes off if you're just chatting.' A pair of trainers is standing neatly by the bed.

Then it is time to interview Joanna. She confirms that the man had paid her pounds 10 for straight sex. Tucking the tenner into her shoe, she says: 'And he's not getting it back either, even if we were interrupted.' Joanna was lucky. It wasn't a night for nicking the girls - just the punters.

(Photograph omitted)