How far would you go to save your child's life? In the second in a series of features on motherhood, Women's Editor Lindsay Jennings speaks to a mum who gave her kidney to her son.

KEVIN Birkbeck appears the kind of man who is not lost for words very often. But as he swings back in his office chair, he is definitely struggling to sum up the gift that his mother gave him just ten weeks ago.

"What can I say?" he says, shooting his mum, Fran, a warm smile. "I don't think you can put it into words. I's a gift that money can't buy, isn't it?"

The wonderful gift that Fran, 57, gave her son just before Christmas was one of her kidneys. Kevin, 38, had always been a sickly child and had an operation at the age of 12 to remove a growth on his bladder. But the damage to his kidneys had already been done. As he grew older, the engineering firm boss felt increasingly tired and his blood pressure was constantly high.

"I was caught in a cycle because high blood pressure damages the kidneys and damaged kidneys heightens blood pressure," recalls Kevin, who lives near Masham, North Yorkshire.

"But in the last two years, it came to a head. The toxin levels in my blood were basically killing me. Then the Christmas before the operation my vision went and I thought I was going blind. I just woke up one morning and I couldn't see. I had my eyes tested and they turned out to be fine. Basically, it was the blood pressure which was causing it. It was 220 over 190 at one point."

Up until Christmas 2003, Kevin had "soldiered on through his bad and good days". Ever the workaholic, he was still continuing to run his company, KJB Engineering in West Tanfield, near Ripon. But eventually he had to admit his body was shutting down.

"I have a theory that you may as well be poorly at work as be poorly at home," he says, causing Fran to roll her eyes, "but it got to the point where it was having a massive physical effect."

Even then, Kevin initially refused to go to hospital for dialysis.

"I read about all the long-term side effects, like strokes and heart attacks, and how it drains the calcium in your bones," he says "I couldn't stand four hours, three days a week in hospital - that would be half my life, and it wouldn't be a life for me."

Which is when Fran, driven on by a mother's love for her son, decided to give Kevin one of her kidneys - and she was never in doubt that her decision was the right one.

"I just couldn't bear to see him so ill, it really upset me," she says. "We didn't discuss it, I just said I'm doing it and that's it. It was a bit worrying, because I thought they might consider me too old, but they didn't."

It took months for the tests to be carried out, but eventually Fran, who lives near Bedale, proved to be a match for her son. The only condition of the operation was that Kevin had to go through dialysis three weeks before the operation because his toxin levels were so high. Without dialysis, the operation was considered too dangerous. But on December 2 last year, Fran and Kevin arrived at Newcastle's Freeman Hospital for the life-saving operation.

"I would be lying if I said I didn't have concerns for my welfare when I got there," says Kevin. "But I also had concerns for my mum. Fortunately they were excellent at the hospital and put our minds at rest."

"I just put my faith in the surgeons," says Fran. "I felt quite positive."

The four-hour operation went well and after three days, Kevin was well enough to get up and walk about. But on day five he heard the news he had been dreading - his body was beginning to reject the kidney.

"They give you all these drugs to stop you rejecting the kidney but on day five, they didn't seem to be working," he says. "It was so nerve-wracking. I'd gone through the whole operation and my mother had gone through it only for it all to be going wrong."

Kevin had to endure a painful biopsy on the new kidney so doctors could assess which antibodies were attacking it. Fortunately, once they had found out, they administered drugs to control it and Kevin was out of the danger zone.

"I really take my hat off to everyone at the hospital. They were absolutely brilliant and kept us positive all the way through," he says.

"I just got better with each day that went by and the yellow colour of my skin faded quite quickly. Before the operation I used to carry on as normal, but I had no motivation or energy. It would cloud my thoughts but after the operation my thinking patterns changed. I just felt a lot sharper, completely different. I've felt tired all my life - and now I feel like I could take on Mike Tyson.

For anyone who knows Kevin, it is not surprising to learn that he was back at work after Christmas - although his mum admits they hid his beloved motorbikes from him immediately after the operation, so at least he stayed grounded for a while.

"It's strange but I got quite emotional afterwards, I just felt so lucky that everything had fallen into place and that I'd been given a second chance," he says.

The operation was also a success for Fran. "I'm just thankful it worked," she says, smiling at her son. "I feel fine and I'm so happy to see him well. It's definitely been worth it."

Swinging back in his office chair again, Kevin ponders once more the enormous gift his mother has given him. But finally, he finds the words.

"All I can say is that I love her to bits," he grins. "What more can I say?"