Ms Lindsell died last December of motor neurone disease. She had gone to the High Court to request that her doctor be allowed to administer the painkiller diamorphine in quantities that would inevitably shorten her life.

She withdrew her case after establishing the principle that doctors could legally administer life-shortening drugs for the relief of mental as well as physical distress.

The Voluntary Euthanasia Society are holding a symposium in Ms Lindsell's memory at the Royal Society of Medicine in London.

The symposium is chaired by The Right Rev. Bill Westwood, Bishop of Peterborough.

Speakers include doctors from Holland, where voluntary euthanasia is widely practised, and Switzerland, where physician assisted suicide is legal.

There are various forms of euthanasia:

• Passive euthanasia - life-sustaining treatment is withheld;
• Physician assisted suicide - a patient is provided with drugs that will shorten life;
• Active euthanasia - a doctor administers life-shortening medication.

General Secretary of the Voluntary Euthanasia Society, John Oliver, said the symposium would contrast the liberal attitude held in parts of Europe with the restrictive legal rules governing euthanasia in the UK.

He said the Lindsell case had helped to clarify the law surrounding passive euthanasia in the UK, and had given the patient the right to decide when life-sustaining treatment should be stopped.

Lethal doses of painkillers can be used

But he said the current legal situation was a "fudge". Although doctors were able to administer life-shortening drugs to relieve pain, not to end life, under a principle known as the doctrine of double effect, the boundaries of acceptable practice were extremely unclear.

"The Lindsell case was educational for doctors, and it nudged legalisation of physician assisted suicide a stage closer," Mr Oliver said.

"We are convinced that it will happen eventually because doctors will wish for it to happen. They will wish for greater protection in law - the doctrine of double effect is extremely uncertain.

"Doctors are frightened to prescribe the right amount of analgesic drugs for patients because they have to watch their backs. There is a terrible thin and fuzzy line."

The British Medical Association is officially opposed to the concept of euthanasia. However, members voted to hold a special conference to discuss the issues at the annual meeting in Cardiff in July.

Euthanasia is 'lamentable'

Chairman of the Prolife Alliance in Scotland, Mike Willis, admitted that there was a momentum for change building up in the medical profession.

He said: "The Voluntary Euthanasia Society is a very, very strong lobbying group, and euthanasia is happening anyway in British hospitals.

"It is lamentable, but it looks inevitable that changes will happen. The medical profession is right behind it - they want legal protection for continuing to do what they are already doing."

Mr Willis said the pro-life campaign would not give up.

"If society does not seek to protect human life we move away from civilisation. The human response, the civilised response is to care. Euthanasia is just a way of getting rid of a problem."

Mr Willis said the hospice movement provided excellent care for the terminally ill.

"People should not be put down like dogs," he said.

A spokeswoman for the BMA said: "There are a range of views in the medical profession but the firm majority view is to oppose euthanasia as being against the patient's interest.