Both Stef and Sharon are aware of the limited impact of their work I don't think we really touch it Stef says

Both Stef and Sharon are aware of the limited impact of their work "I don't think we really touch it," Stef says. "You put someone in prison, there'll always someone who'll come out to take their place."THE DRUGS EDUCATION OFFICERPC Dick Westland fixes the class of 13-year-old girls from Norbury Manor School with a time-is-of-the-essence look: "You need to have information about drugs, and you will need to have opinions, because you will need to make decisions I'm not here to say 'Don't take it'," he continues "Don't tell me who your dealers are. "You're not involved in anything like that, are you?" she asks. " 'Course not, Old Bill just shown that, haven't they?" he replies."You could say we wasted out time," says the squad head DI Peter Spindler later, "but you never know until you try." The 17-strong squad has to be highly selective about whom it targets, because there are only resources to deal with a fraction of the dealers in the Metropolitan Police sector (roughly a quarter of London).

After half an hour, they have found nothing; the officers are on the point of leaving (and de-arresting) when the suspect's mother turns up There is an awkward silence. The sniffer dog sniffs, drawers are opened, mattresses turned, and the team keep up a running banter. Over an hour later, the "target" stirs and the team moves in There is a tense start. The man thinks the two arresting officers are aggrieved relatives, who've come round to sort him out.

"One of them reckons he's a face in Battersea, but he's third rate," he jokes as the officers relax into the search A baseball bat stands propped by the front door. They pull up in a suburban street and settle back for the predicted emergence of the man at 8.30am, keeping in radio contact with four colleagues parked nearby.They discuss careers, the Queen's corgis, gypsies in Orpington, tales of being mistakenly chatted up in night clubs by dealers ("He was stupid enough to give me a card with his number - we nicked him the next week," says Sharon) It gets to 8.30am and nothing happens. If someone has a pounds 500 suit and says they are unemployed, that tends to stick out. In your own mind, you try to establish what is normal." A particular profile, even that of a white western female, can set alarm bells ringing if the flight they are on is deemed high-risk. "Someone will break the plane of your consciousness and you will step back a for a minute," Gyseman suggests.As he finishes work, hanging around just to see in a 3pm flight from Pakistan ("Everyone on that will be suspect"), Gyseman muses on life on the customs bench: "It is a closed, claustrophobic environment - you are being paid to be suspicious of everyone passing in front of you." The job has its rewards, though "When you take out heroin, you are protecting society.