By common consent, Kay Gilderdale was a devoted, loving mother who unstintingly nursed her desperately ill daughter Lynn for 17 years at the family home.

Like Frances Inglis, the mother jailed at the Old Bailey last week for injecting her brain-damaged son with a lethal heroin dose, Gilderdale was considered by her family to have her child's best interests at heart.

But the two cases have reignited the debate surrounding euthanasia and the "right to die", with pro-life campaigners insisting they illustrate more starkly than ever why assisted suicide should remain illegal.

Relaxing current assisted suicide laws would leave vulnerable people without adequate legal protection and help forge a mindset that the lives of the sick or disabled are less worth living, according to Care Not Killing.

Yet groups such as Dignity in Dying, which campaigns for greater patient choice at the end of life, insist a clearer distinction needs to be made in law between acts to end a life borne out of love and those motivated by greed or malice.

What is clear is that 31-year-old Lynn Gilderdale led an "unimaginably wretched" life through illness which led her to attempt suicide, consider ending her days at Dignitas, the Swiss-based assisted suicide clinic, and sign a "living will" after saying she "feared degeneration and indignity far more than I fear death".

Apart from occasional, and dreaded, hospital admissions, life for her rarely stretched beyond the four walls of her bedroom at the family bungalow in Stonegate, near Heathfield, East Sussex.

Born on September 20 1977, she was an active and sport-loving child, an accomplished musician and adored sailing, swimming and cycling before her health faltered.

Struck down by the chronic fatigue illness ME at the age of 14, she was left paralysed, unable to eat, sit up or swallow. She later had her dreams of motherhood dashed after she went through the menopause early.

In frequent agony, she received a constant supply of the painkiller morphine through a syringe driver and a Hickman line connected to a vein for her frequent injections.

She was fed by a nasogastric tube and communicated with her parents, who divorced in around 2001 but remained equally supportive of her, using a sign language technique they honed themselves.

Privacy was virtually non-existent for Miss Gilderdale, with her requiring help for the most basic human functions. The only solace she gained was from her handheld computer which she used to communicate to other people with illnesses.

It was using this that she laid bare her frustrations at her condition on the Live Journal forum, describing her "miserable excuse for a life" and adding: "I can't keep hanging on to an ever-diminishing hope that I might one day be well again."

In another section, she said she was "tired and my spirit is broken" and she would grab an opportunity to leave the world "with both hands".

And so it was that at 1.45am on December 3 2008, Miss Gilderdale called her mother into her bedroom after she gave herself a large dose of morphine, telling her: "I want the pain to go."

Gilderdale, 55, spent an hour talking to her daughter, telling her it was "not the right time" and triggering the start of what the prosecution described as the "fateful 30 hours" leading to her death.

At 3am that day it was said Gilderdale gave in to her daughter's wishes to help her and she gave her two large doses of morphine which she self-administered.

When it later emerged that the dosage had not achieved Miss Gilderdale's suicidal aim, her mother is said to have searched the house for tablets, including Diazepam, Temazepam and Zopiclone, which she crushed with a pestle and mortar and administered via her nasogastric tube.

Around 24 hours later, at 2am on Thursday December 4, Gilderdale gave "two or three" further doses of morphine directly into the Hickman line and later gave her three syringes of air into her veins to cause an air embolism, the trial at Lewes Crown Court heard.

After giving her daughter a further eight tablets, Gilderdale telephoned an assisted suicide organisation in the hope of gaining further advice.

During those 30 hours, it was said Gilderdale also trawled the internet, with search terms relating to morphine overdoses and the voluntary euthanasia campaigner Dr Philip Nitschke, dubbed "Dr Death".

Miss Gilderdale died at 7.10am on December 4. A post-mortem examination found she died from morphine toxicity.

The sequence of events leading up to Miss Gilderdale's death was given by her mother to the family GP, Dr Jane Woodgate, who was telephoned on the morning of the death by her former husband Richard Gilderdale.

But the court was told that it was not possible to determine from blood analysis the account given by Gilderdale of the volume of drugs given to her.

And because toxicology tests failed to establish whether Miss Gilderdale died from the morphine she injected herself, or the drugs her mother was said to have given her, the more serious charge of murder was not pursued.

The decision to prosecute Gilderdale was made before legal clarifications were made in England making it easier for those helping a relative end their life to know if they would face prosecution.

In July last year, Director of Public Prosecutions Keir Starmer QC outlined 16 "public interest factors" in favour of a prosecution and 13 factors against taking legal action to bring clarity to existing assisted suicide legislation.

The move came after the Law Lords backed multiple sclerosis sufferer Debbie Purdy's call for a policy statement on whether people who help someone commit suicide should be prosecuted.

In Scotland, veteran MSP Margo MacDonald, a Parkinson's disease sufferer, launched a move this month to legalise assisted suicide.

If supported by MSPs, the End of Life Choices Bill would make Scotland the first part of Britain to change the law and allow anyone over 16 to request help to die.

It stipulates that the person must be diagnosed as terminally ill or permanently physically incapacitated, and finds life intolerable.

Gilderdale opted not to give evidence in her defence at trial, but four years ago she painted a depressing picture of the devastating effect ME had on their lives.

In an interview with the Daily Mail published in July 2006, she said: "It's like she's in limbo.

"If someone dies, you mourn them, then you get to the stage where you know that person is gone and you move on. But Lynn is neither one nor the other.

"She is stuck in that room, not dead, but not alive properly. If I didn't believe, and she didn't believe, that one day she would get better then I don't think it would be right for her to go on suffering like this for a whole lifespan of 70 or 80 years."

Her trial heard Gilderdale retained hope that one day she might return to normal health and she spent hundreds of pounds on a new treatment for ME.

She also kept the support of her family who accompanied her to court each day, including her son Steve, and her former husband, a retired Sussex Police officer.

Mr Gilderdale and his ex-wife, whose full name is Bridget Kathleen Gilderdale, married in 1973 and separated in around 2001. He has since remarried but remained supportive of his daughter, describing her as his "best friend".

He defended his former wife in the witness box, saying they both "fought every minute of every day" for their daughter, who he said regarded them as "a team".

He also said he could never imagine his former wife trying to kill their daughter.

Indeed, in the days after she was charged by Sussex Police in April last year, the family released a statement in which they expressed their "extreme disappointment and sadness" at her prosecution.

They said they would work to help recognise her as "the dedicated and loving mother of Lynn who cared unreservedly for her daughter over so many years".

They told of their hope that recognition of her devotion to Miss Gilderdale would help resolve matters in the "coming weeks".

As it turned out, their nightmare has been far longer lived.