It’s 3.30 in the morning and prostitute Megan has just told me she’s worried about us getting beaten up as her heroin dealer’s about to arrive.

She has just been pulled over by undercover officers for loitering and two police cars are flanking us in Lowbrook Road, Ilford.

She’s worried that if her dealer sees her talking to the police he’ll think she has tried to get him into trouble.

Megan – not her real name – became a prostitute at the age of 13 after being sexually abused by her brother, step-dad and a family friend and works to feed her crack and heroine addiction.

It’s freezing cold and despite the fact that I’m wearing two pairs of socks, boots, a huge coat and, I’ll admit, a thermal vest, I’m shivering.

However 34-year-old Megan, who’s clad in a low cut short dress and lacy tights, seems impervious to the cold. She’s one of numerous girls out working the streets playing an elaborate game of cat and mouse with the police.

Prostitution is a dangerous job and in her two decades on the streets Megan has been held at gunpoint, beaten unconscious and even abducted.

“I was held captive for three days by a guy who was a bit mad,” she says. “He kept saying his mum and dad were telling him to kill me. It was really scary.

“At times like that, I feel like I should stop, and then I get on and it passes.”

The hours the girls work are gruelling with Megan starting at 10pm and ending her shift at 7am. She does this seven days a week.

“I’m not a prostitute, I’m a working girl,” she says. “In my mind a prostitute is someone that does it without condoms but I try and keep it as respectable as I can, I do my job and have a habit to feed.”

This evening Megan is issued with a caution and told to move on. The police give two cautions if the offence occurs within three months and on the third, the girl is arrested.

My evening with the Loxford Safer Neighbourhood Team started at 10.30pm with a briefing in a rundown office in Valentines House, Ilford Hill, Ilford.

Sgt Lee Wilkinson briefs the uniformed and plain-clothes officers, together with two Romanian policemen who are joining the team for a couple of nights.

It’s the fifth night of Operation Clear Water which ended on Friday, and the number of girls on the street has steadily declined over the week indicating it’s working.

In any case, it was certainly the first briefing I’d been to which incorporated human rights and bodily fluids all in one breath. Within an hour I’m loaded into a discreetly marked police car and taken to Redbridge’s CCTV control room in Ley Street, Ilford. From here an officer is monitoring the screens and directing the teams on street level like a military general directing troops.

By midnight the temperature is dropping and the officers are well into their shifts issuing cautions, making arrests and using the dispersal zone with impressive efficiency.

The zone means police can make groups of two or more people leave, and is one of the tools they use to combat prostitution. The dispersal zone, which covers Ilford Lane and 150 metres of the adjoining streets, will be in force until March 2013.

Before I know it, I’m in and out of a car again and am walking down used condom and baby wipe littered alleyways frequently used by prostitutes and their clients.

Mr Wilkinson said: “There are girls that are forced into it, some that do it for the money and others that have addictions. Lots of the girls have no income. Loxford is improving, I know people don’t think it is. Every month crime goes down.”

Then I’m back in the car with plain-clothes officers Dave and Pete when we spot a silver Nissan on a corner where they had earlier moved on two prostitutes.

Dave steps on the accelerator and the car roars in front of the Nissan blocking them in. Before I’ve even taken my seatbelt off Pete’s out of the car and asking the men what they’re doing.

It’s clear the men have been drinking and proudly announce that they don’t speak enough English to answer any questions. Pete radios for the team that Nicolae Dumitrescu, the Romanian officer, has joined and seconds later their car comes tearing up the street, blocking the Nissan in from behind.

The shock on the men’s faces as a fully uniformed Romanian police officer gets out the car, is for me, one of the highlights of the evening. After explaining the law and issuing Acceptable Behaviour Contracts the men are sent on their way.

Then we’re back to cruising down Ilford Lane, with Pete and Dave both singing along to Madonna’s Material Girl on the radio. We take a side turning where we spot a skinny, wide-eyed man standing in the middle of the street.

Pete winds down the window and asks the man how he’s doing. In response “skinny” asks if we’ve been sent by someone called Khan. After a brief pause he says something I can’t quite hear about heroin and �15 and then, almost as an after thought, asks “you’re not old bill are you?” to which my companions answer in unison “yeah”.

Both officers jump out of the car, one donning blue rubber gloves and starts searching the man while the other cases the area for drugs.

The evening is relentless and I’m surprised how easily they maintain their upbeat, but unmistakably professional manner into the depths of the night.

Dave said: “The girls have sad stories but they are still breaking the law. We caution them but we still speak nicely to them. We have a rapport but with that they know, if they carry on, we will arrest them.”

After a few more stops all the teams make their way back to base to fill out paperwork about the night’s events and then get ready to do it all again tomorrow.