"Two scratchcards and a pack of 20 Cannalights please."

Hard as it is to imagine, one day in the future cannabis cigarettes could be as much of a cornershop staple as cough sweets and cartons of semi-skimmed.

"Got anything a bit stronger?"

Calls to legalise cannabis are back in the headlines, this time following confessions from seven members of the shadow cabinet that they have smoked dope.

The debate on relaxing the law on pot stretches back more than 30 years. Yet increasingly it seems to return with renewed vigour.

On Sunday, Liberal Democrat leader Charles Kennedy became the first leader of a mainstream party to say he favoured the decriminalisation of cannabis.

Earlier this year, the strictly establishment Daily Telegraph astounded many of its readers by calling for soft drugs to be legalised.

Everyone acknowledges that legalising cannabis would be a huge step for any government, but with what effect? What would Britain be like if dope were as freely available as alcohol and cigarettes?

1) Effect on take up

Decriminalisation: Smoke it, but don't sell it

More than anything, the effect would depend on how many people become regular users.

Just because cannabis would be available over the counter, the take up rate would not necessarily rocket.

As the only European country where cannabis is widely tolerated by the authorities, Holland provides a useful comparison for what might happen in the UK.

Research by the Netherlands Institute of Mental Health and Addiction - the Trimbos Institute - suggests relaxing cannabis laws will not necessarily lead to a long-term rise, at least among children

The institute found that while 41% of 15-year-olds in the UK had tried cannabis, with 24% using the drug in the previous month; in Holland 29% had tried the drug, while 15% had used it in the previous month.

2) Hard to go without

What does decriminalisation mean?

Personal use tolerated Producing, dealing and possessing cannabis illegal Dutch 'coffee shops' sell small quantities to adults Holland, Germany and Italy tolerate personal use Spain applies administrative sanctions for public use

Those who do develop a taste for the drug may find it hard to go without, especially if it is freely available. Despite claims to the contrary, cannabis is addictive, according to a survey by American National Institute of Drug Abuse.

The research found three-quarters of those who gave up cannabis had cravings for it, and 70% switched to tobacco in an attempt to stay off. Almost half said they became irritable after giving up, and many were bored as a result of coming off the drug.

3) Relaxing qualities

Of all its so-called qualities, cannabis is best known as a relaxant. That might have appeal in a country where we work the longest hours in Europe - 43.9 hours a week - and an estimated 40 million work days each year are lost through stress.

Cannabis can ease conditions such as high blood pressure, which exacerbates stress and can lead to premature death.

Britain's more "chilled out" mood might also be reflected on the streets, where post-pub fighting has become an unwelcome occurrence in many town centres.

In the wake of England's virtually trouble-free defeat at the hands of Portugal during the Euro 2000 football contest, police in Eindhoven, Holland, said the drug had relaxed fans.

4) Society slows down

The relaxing effect can go too far. Research shows the drug affects almost every system of the body, slowing down reaction times, causing drowsiness and confusion.

Britain might also become a more forgetful society. Even in small doses, dope smoking is known to cause short-term memory loss. In extreme cases it can cause hallucinations and paranoid delusions.

5) Drug tourism

Early drug tourist: John Lennon at the Amsterdam Hilton

Already a sought-after destination among overseas travellers, Britain could expect to see a jump in the 25 million overseas visitors it gets every year as dope smokers from abroad set out to enjoy our liberal drugs law.

That would be good news for the economy, but drugged-up visitors are not to everybody's liking. Authorities in Holland have taken measures to limit the supply of soft drugs after Amsterdam became swamped by drug tourists (many from Britain) in the 1990s.

6) Fall in fertility

The birth rate could drop because marijuana suppresses ovulation and retards sperm production. Sperm counts have slumped 50% in the past five decades and it already takes an average couple 11 to 12 months to conceive.

7) Cancer increase

Efforts to cut tobacco related-illnesses in recent years could be undone with cannabis. A report by the British Medical Association found smoking a cannabis cigarette leads to three times greater tar inhalation than smoking a tobacco cigarette.

8) Curing qualities

Bearing in mind the above points, it could be a long time before society feels it is ready for the changes over-the-counter cannabis would bring.

Perhaps more realistic is its legalisation for medical purposes. There is evidence of the drug helping sufferers of migraines, multiple sclerosis, glaucoma and even anorexia - it stimulates the appetite. Prescription for medical purposes could therefore reduce the National Health Service's dependence on other costly drugs.