The best analysis is a jigsaw of information built up from different sources. The majority of surveys are small-scale, local studies, which - unsurprisingly - tend to be located in those areas with significant problems. There is clearly a danger that the large number conducted in London, Glasgow, Manchester, Liverpool and Edinburgh will skew the national picture.

However, the information below is a reasonable indication of the scale of the drugs problem in Britain today:

• Every other young person between the ages of 16 and 25 says they have taken drugs - about 3.5 million people. A third of these are still using them.
• By the time they take their GCSEs, two in five schoolchildren will have taken a drug.
• Cannabis is responsible for 80% of drug use. Two in five of those who have used the drug in the last year will have also used another type of drug.
• About one in seven young people (14%) will have used amphetamine or LSD, one in ten, magic mushrooms or amyl nitrate, and about one in twelve (8%) will have tried ecstasy.
• Use of harder drugs (heroin, cocaine, and crack) is at around 1-2% of the population. Less than 1% will have ever injected a drug.
• Males are far more likely to be serious drug misusers than females - the ratio has remained steady at 3 to 1.
• Over half of those presenting themselves for treatment are in their twenties; nearly a fifth are in their early thirties; and over one in 10 are aged between 15 and 19.
• Drug users are believed to carry out property crime costing more than �2.5bn each year to feed their habits. Six out of 10 suspects arrested by police test positive for drugs.

Britain's biggest drugs charity, Turning Point, said the number of people it helped in 1997 rose by 12% to 29,599. Not only were there more drug users in need of treatment, but they were younger than ever. At one Turning Point centre in west London, more than half of new people seen by the charity were under 18.