Seizures
The number of drugs seized and people arrested vary greatly from year to year. This generally reflects the activity of the police and customs and each, rather than the amount of drugs available.
For example, in 1998 the quantity of cannabis plants increased by over 40 per cent from the previous year due to the police finding a single but very large warehouse of cannabis plants in a remote part of Scotland. This did not reflect any great increase in the quantity available, just the result of one very large find. Similarly, police in Lambeth are no longer charging people for the possession of cannabis. This will no doubt reduce the number and quantity of cannabis seized, and, due to a re-allocation of police time and resources, might increase seizures of other drugs such as cocaine and heroin in this area.
Other drugs, such as LSD are difficult to detect, particularly if impregnated in paper while some are simply not seized by police. Seizure statistics do not cover solvents or the use of legal drugs such as some tranquillisers, magic mushrooms, GHB, ketamine, amyl nitrites and herbal highs.
Drug seizure statistics are helpful however in that they can, with care, indicate longer-term trends in drugs most commonly being imported and distributed in(to) the country. But they are not reliable on their own. Other more reliable sources of drug use levels are the British Crime Surveys (BCS).
What the statistics do show is that cannabis is consistently and by far the drug most seized, followed by amphetamine and ecstasy. In line with drug use estimates seizures of cocaine are increasing, as are seizure quantities of ecstasy.
Table 1. Number of offences 1998.
| Offence | No of people |
| Possession of cannabis | 89,129 |
| Possession of other drugs | 32,799 |
| Possession with intent to supply drugs | 9,290 |
| Unlawful supply of drugs | 6,974 |
| Unlawful production of cannabis | 3,190 |
| Unlawful import or export of drugs | 1,152 |
| Other offences | 1,272 |
| Permitting premises to be used for unlawful purposes | 825 |
| Unlawful production of drugs other than cannabis | 317 |
| Total | 127,919 |
Drug purities
The seizure statistics reveal the average purities of drugs seized by police. These vary from area to area and also between drugs seized once they are in the country - and those seized at ports of entry by customs. This is because drugs already in circulation are cut to increase profits (particlarly powder drugs such as cocaine and amphetamine).
Table 2 UK average drug purities 1998 (%)
| Inland | Imported |
| Cocaine | 53% | 74% |
| Crack | 85% | 86% |
| Heroin | 35% | 49% |
| Amphetamine | 14% | 55% |
Value of the drugs market in the UK
With these limitations in mind the Office for National Statistics (ONS) have tried to estimate the size of the drugs market in the UK, based on a number of assumptions. These include the number of drug users, the quantity of drugs consumed, street versus import purities (from police forensic tests) and the proportion of drugs seized at import (this is done using the capture recapture method described in How many drug addicts are there?). Using their best estimates, the ONS calculates that the value of the drugs market is between £3.9 and £8.5 billion a year.
Whether it is at the bottom or top end of this range depends on the customs seizure rate. If only five per cent of drug imports are halted, then illegal drug transactions add £8.6 billion to the UK Gross Domestic Product (GDP - how much we buy and sell in the UK). This is just over one per cent of the total GDP.
Updated January 2005
