A grandmother who became the first person in the UK to donate a kidney to a stranger a decade ago has told how she was considered "mad".
Kay Mason, 73, from Welwyn Garden City, Hertfordshire, fought long and hard for the right to give her kidney to somebody she had never met.
She spoke out on the issue and gave feedback during a consultation process which led to a change in the law.
The former palliative care nurse has never met or written to the person who received her kidney in the summer of 2007.
She said: "The fact that we've never met, even after all these years, is fine by me.
"I suspect many people would give to a friend but I do take great joy from having given to a stranger.
"Life can be so unfair but to me this is nothing but a wonderful thing."
Ms Mason said it had never made any sense to her why she was unable to donate to a stranger.
"To be honest it seemed I faced a real struggle everywhere I turned back then," she said.
"There had been a 'kidneys for sale' scandal and if you weren't related you had to prove you knew the person.
"The thinking was you had to be mad to want to give a kidney to a stranger and, if you were mad, you couldn't be allowed to give.
"But I was perfectly sane.
"I'd done my homework and found out that people were dying for want of a kidney.
"My kidneys were healthy, I was already 60 and I didn't have kidney disease so I reckoned I could survive comfortably with just the one.
"To me a stranger was only a friend or acquaintance I hadn't met.
"The more I looked into it the more I discovered. For instance I heard of a story where someone needed a kidney and an enormous amount of pressure was put on a particular family member to become a donor, something they didn't particularly want to do."
The Human Tissue Act 2004 came into force in September 2006 and Ms Mason's surgery was carried out the following summer at the Royal Free Hospital in London.
Since then, 580 more people have donated their kidneys to strangers.
Gareth Jones, who leads kidney transplantation at the Royal Free, said: "Kay was a trailblazer when it came to non-directed kidney donation and the UK is now a world leader in this area.
"Kay's precious gift has been life-changing for so many people because where she led, others have followed."
Bob Wiggins, chairman of the charity Give a Kidney, said: "Kay's fight was instrumental in helping change government policy.
"What she began 10 years ago has led to hundreds of kidney patients being given opportunities for transplants they may not otherwise have had.
"Times have changed enormously over the last 10 years and every transplant unit in the country has a programme for non-directed kidney donors.
"However, there are still more than 5,000 people in need of a kidney in the UK and around 250 people die each year because there are not enough organs available from deceased donors, so there is still a need for yet more people to consider donating in this way."