He knows all of this because afterwards, as with his previous 27 trips, he discussed the experience with his fellow 'trippers' and added the findings to his painstakingly compiled collection, Do Not Exceed The Stated Dose.

Far removed from the dull, addled stories of the 'and this one time, man, I was so wasted...' variety, familiar from many a student diary, Do Not Exceed The Stated Dose is a wry, informative collection of 28 LSD 'experiments' conducted over six years. It's also a stand-out example of a growing informal drug-insiders' network, users coming increasingly to lean on their peers as the most reliable source of information.

Information from more established sources, government bodies or drugs groups in receipt of public money, has, in the past, seemed limited: understandable, perhaps, given official reluctance to be seen to be endorsing drug use. So finding out the lowdown on drugs (other than that they can lead to a life of poverty and crime) has meant users doing it for themselves. This is the bulletin board principle, and it's not surprising that the internet has become a key resource. Information and advice on new substances is readily available by simply asking a chatroom and drawing on hundreds of other people's experiences. The first port of call is rarely government-produced literature.

Greensworth (his drugs moniker), a 28-year-old engineer from north London, explains that his collection grew from these first few experiences, kept as a roughly printed sheaf, developing into a third edition: a handsome cream-bound set of seven copies distributed among the 32 guinea pigs. Each of the copies is to be cared for, read and then passed on to the next in the list. They were also made available to anybody showing interest in taking LSD, on a safety-first principle. Besides being of interest as a sort of collective drugs diary, Do Not Exceed The Stated Dose also contains a guide for first-time drugs users which, though specifically for the use of LSD, is relevant for all drugs.

Advice ranges from planning your trip in advance and choosing a comfortable base, away from tall buildings, in which to experience LSD, to a checklist of foodstuffs, clothing and gadgets to have handy during the trip.

The model for this endeavour is Dr Alexander Shulgin, the infamous pharmacologist from California, who is responsible for the creation of over 120 new substances. His 1991 book, PiHKAL, Phenethylamines I Have Known and Loved, is the ultimate drug diary, documenting hundreds of first-hand experiences.

Reading or hearing of someone else's experiences is how many drug-taking judgments are made. Perhaps that is why Shulgin's PiHKAL has never been out of print, and why the internet is bursting with sites offering first-hand accounts. One website, Urban75.com, offers 'bullshit-free' advice .

Another example is the site ecstasy.org which claims over 9,000 daily visitors. Its purpose is to make accessible objective, authoritative and up-to-date information about ecstasy. A section allows users to submit their own drug diaries under such headings as 'relationships', 'positive experiences' and 'disillusionment'.

Some of the descriptions make you balk with their pseudo-poetry. Here is a first time account entitled 'Empathy Through Ecstasy': 'A wave of warmth overcame me on my way down. For the first time in my life I knew what empathy felt like. I thought that everyone was my friend. The world seemed like a better place.'

But such sites do not merely offer blissed-out dispatches. 'I dropped three white doves and a fido dido [ecstasy pills]...' writes another contributor. The effects were 'too strong', resulting in vomiting and a visit to the paramedics. 'For the next couple of days afterwards I was an emotional wreck, paranoid as hell, shaking... '

Other sites provide more wide-ranging information on a variety of drugs. Due to the independent nature of the site erowid.org, it is now cited by leading research agencies as a useful first port of call for anyone who is keen to learn more. Besides the online information about psychoactive plants and chemicals, erowid.org also lists a compilation of experiences and articles contributed by users, parents, health professionals, researchers, teachers and lawyers. It's certainly popular enough: the site claims over 18,000 visitors each day and around 2.8m unique visitors on a yearly basis.

Greensworth claims that the 'just say no' approach is never going to work with the curious. So it's better to make sure, he says, that the potential user says a well-informed yes.