Margo MacDonald, the independent MSP, has tightened up the proposals in her assisted suicide bill after receiving around 400 responses during a now-ended consultation.

She was supported yesterday by Edward Turner of the English organisation Dignity in Dying, who became involved in the issue after his mother visited a Swiss clinic to end her own life rather than face an agonising death at the hands of the degenerative disease PSP.

Her story was told in an acclaimed BBC dramatisation A Short Stay in Switzerland, starring Julie Walters.

Mr Turner said: "Margo's proposals have some really important safety checks. I welcome the moral leadership which I think Margo is taking on this issue and it will strike a chord with the vast majority of the public."

Mr Turner had lost an uncle and his father to degenerative diseases when his mother Anne, a doctor, was diagnosed with an aggressive form of one of the worst, PSP, which shuts down all muscle functions, including the ability to blink or swallow.

The response to A Short Stay in Switzerland had been "utterly phenomenal" with audience approval ratings surpassing those of the Dr Who Christmas episode.

Ms MacDonald has narrowed her proposals to cover only three specific categories of people who believe their lives have become intolerable. It includes those with a progressive, degenerative conditions; those who have suffered a trauma such as crashes or sports injuries, leaving them entirely dependent on others; and those with terminal illness.

The parliamentary authorities still have to analyse and publish the consultation on the End of Life Choices (Scotland) Bill, but Ms MacDonald said there had been around 400 responses.

She cited an STV poll this week showing 75% of the public agreeing with the principle that people should have the right to choose when they die, saying this was in line with most tests of public opinion.

But she admitted that this will not be reflected in the outcome of her own consultation because of a strong push by organised campaigners against the idea.

Ms MacDonald, who has Parkinson's disease, said the poll result is similar to other surveys, adding: "I'm inclined to think we are absolutely on the right track in the Scottish Parliament in testing this now and in trying to frame a bill."

Mr Turner, said his mother's illness would have left her "completely paralysed and trapped in her own body".

He said: "I thought it was unjust my mother had to leave her own country in order to have a dignified death.

"It's hard for us who are not facing the end of life to understand the desperation that people have. The choice that they have is not between life or death, it's the choice between a good death and a bad death.

"We do have a duty, a compassionate duty, to listen to the desires that mentally-competent patients make about their own life."

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