The suicide expert known as Dr Death today launched a series of public meetings in Britain to demonstrate how to end life effectively.

Philip Nitschke, who helped four people to die when euthanasia was briefly legalised in Australia, spoke to an audience of the middle-aged, elderly and sick after spending nine hours in detention at Heathrow arguing with immigration officials.

He was stopped at the airport over his testing kit, which will enable people to ensure that the poison they have chosen to kill themselves with is sufficiently strong to end their lives.

Officials fingerprinted him and searched his bags, becoming particularly suspicious of a device containing syringes. Dr Nitschke explained that it was his Euthanasia Drug Test Kit.

He persuaded the authorities to let him stay, although they told him he must leave by the end of the week.

During his tour Dr Nitschke will hold meetings, today at a hotel on the Dorset coast, then invite his audience to join his organisation Exit International, enabling recruits to go into a closed session where he will discuss in detail the pros and cons of various methods of suicide.

"Our organisation is now 3,500-members strong," he told The Times. "Obviously a lot of people leave the organisation, too."

Dr Nitschke earned admiration and notoriety when he carried out the world's first legal assisted suicides during the 1990s after the Northern Territory of Australia allowed the procedure, only for the federal Parliament in Canberra to outlaw it again.

At a flat in Bayswater, west London, Dr Nitschke gave The Times a preview display showing how the kit allows members of the public to ensure that the deadly liquid they buy, usually from mail order suppliers, is the correct concoction and remains potent.

Dr Nitschke makes no secret that he advocates Nembutal, the barbiturate that killed Judy Garland and Marilyn Monroe, and is used wherever euthanasia has been legalised.

The drug, commonly administered by vets, is banned for human use in Britain and one of the few places where it can be bought over the counter is specialist shops in Mexico. He calls it "the peaceful pill".

Dr Nitschke's British tour will take him to the retirement meccas of Bournemouth, Brighton and Stroud before a final outing to Glasgow.

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