MPs last night approved controversial research on human embryos which British scientists claim could unlock cures for chronic diseases such as Parkinson's and Alzheimer's.
After an impassioned debate and despite fierce opposition from pro-life campaigners, the House of Commons voted by 366 to 174, a majority of 192, to permit stem cell research on embryos up to 14 days old.
The issue was settled on a free vote, enabling MPs to vote according to their consciences.
It followed strong assurances from the Public Health Minister, Ms Yvette Cooper, that stem cell research did not represent a "slippery slope" to human cloning, which would remain illegal.
Ms Cooper said the research could hold "the key to healing within the human body" - giving hope not only to those suffering from degenerative dis eases but also cancer and heart disease victims.
"There are immense potential benefits from allowing this research to go ahead," she said.
A leading opponent of the move, the Conservative MP for Congleton, Mrs Ann Winterton, said it was a "cruel hoax" to claim that voting against the regulations was tantamount to depriving the sick of a cure.
Mrs Winterton said: "It is both untrue and unspeakably cruel to tell families who suffer from genetic disease and other problems that a vote against cloning is a vote against providing them with any hope for the future."
The Shadow Health Secretary, Dr Liam Fox, said he was morally against the use of embryo cells and had not been convinced there was no alternative. But it was unrealistic to think such research could be halted, and so tough rules were needed to set the moral boundaries.
A heartfelt plea to approve the change came from the Labour MP for Aberdeen South, Ms Anne Begg, who uses a wheelchair because of a rare degenerative disease. Stem cell research had "enormous potential" for people suffering from a wide range of conditions and scientific and medical opinion was almost unanimous in its support, she said.
The Labour MP for Slough, Ms Fiona MacTaggart, who said in last Friday's debate on the issue that she was both infertile and a multiple sclerosis sufferer, also appealed, in a voice quaking with emotion, for MPs to back the change.
The Liberal Democrat health spokesman, Mr Nick Harvey, said almost everyone had experience of at least one person suffering a long-term degenerative disease and would have witnessed the "slow death" they were suffering.
Nobody would want to thwart research that could put an end to those conditions, he said, and there would need to be "very good reasons" to halt it. He said he had listened carefully to the arguments for and against and had come out in support of the research.