LESS than 10 years ago the effort of walking five minutes to the shops was too much for Sandra Middleton.

A mystery illness, believed to be genetic, had been gradually eroding her kidney function and pushing up her blood pressure for decades.

The retired school secretary from Dundee, 63, said: “When I came home from work, that was me. I was putting my feet up and falling asleep. Even in work instead of running around with messages I had to write them out and hand them to other people to take round.

“We live about a five-minute walk from the shops but I wouldn’t walk, I would take the car. I wouldn’t walk anywhere.”

By June 2003, Sandra needed a kidney transplant to survive. Her brother was tested first but was not a suitable match, so husband Brian stepped in.

He said: “I was delighted to be a donor match. We’d been married 30-odd years. I wasn’t a great match but with all the drugs they’ve got now, they’re able to do a lot more. I worked with [technology firm] NCR in Dundee at the time and they were very helpful and very supportive so financially going through the operation, there was no problem from that angle. I was able to go back to work about eight weeks later.

“There was a big difference for Sandra. She felt a lot stronger. It changed both of our lives, to be honest. Near the end, before the operation, it was always a thought to go out, but now Sandra is able to go out the same as I am.”

The case is one of a loved one donating a kidney to save the other’s life – but what about a donor market?

“It makes me uncomfortable,” said Mrs Middleton. “If it’s regulated on the NHS that’s better because people are then doing it because they want to – but I’m still not sure.”