Dan has described Jen as the “bravest woman in Scotland”, but yesterday she played down her part in saving his life.

“I did this for selfish reasons in a way, because it brought me my husband back,” she said.

“There was no question about what I had to do. Nobody approached me about this.

“I approached the hospital and asked them if I could donate part of my liver after reading about the procedure on the internet.

“They told me I could pull out right up until the day of the operation, but I didn’t think twice about doing it.”

Doctors said the chances of Jen’s liver being a match for her husband were slim, but after several tests, she was declared suitable.

And, although the risks were high for Jen as the donor, it was Dan who did most of the worrying for her.

“As adamant as Jen was about doing the operation, it was the hardest thing I’ve ever had to do,” he said.

“On the one hand, if I didn’t get a transplant, I wouldn’t be here. On the other, Jen said to me, ‘If the shoe was on the other foot, what would you do?’ 

“I would have done it in a heartbeat. We’ve got our whole life in front of us. Not a day goes by when I don’t look at Jen and remember what she did for me.”

Jen, a student veterinary nurse, has now almost completely recovered from the 10-hour operation, at Edinburgh Royal Infirmary on January 16, while Dan, a New Zealand-born IT worker, still has some way to go.

“There is no feeling of impending doom hanging over me any more,” he said. “I have so much to look forward to and I feel like my life has been given back to me.

“I can’t find the words to thank the medical team enough. Jen has saved my life and they gave her the opportunity to be able to do that.”

Live donor liver transplantation has been used in worldwide for more than 15 years, but was first carried out in the UK last July when a Leeds father received part of his son’s liver. 

A healthy individual can live without a full-sized liver, because it is much bigger than needed and is capable of growing back to its normal size within weeks. 

John Forsythe, director of the Transplant Unit, said: “We are delighted that the operation has gone so well. Both Dan and Jen are now back at home, and doing well. 

“This operation marks the start of another potential option for patients on waiting lists. At the moment there is a 20 per cent mortality rate for people waiting. This option won’t be available for everyone, but it will work for some people.”

Surgeon Murat Akyol added: “This has been a truly extraordinary gift from Jen to Dan.”