His son was suffering from a rare liver condition and it was unlikely that surgeons would find a donor liver in time. So David decided to step forward and risk his life to donate part of his own liver to save his desperately ill son.
Surgeons removed a fifth of David's liver and transplanted it into his son - who has now made a complete recovery.
Daniel's mum, Fiona, 42, a pre school teacher, says: "I'm just so grateful to David for saving our son. It was a risky operation for him, but he never hesitated to risk his own life to save Daniel.
It was terrible seeing them both go through the operations at the same time, and I had to go between one hospital ward and the other to help them both. But luckily they have both recovered. To see Daniel doing so well now is amazing.
Little Daniel, now three, was diagnosed with the life-threatening condition biliary atresia when he was just 12 weeks old.
Biliary atresia is a serious but rare disease of the liver that affects newborn children. It occurs in approximately one in 10,000 babies and it means that the loss of the bile ducts cause bile to remain in the liver and damage it. It can lead to liver failure which can only be cured with a transplant.
Fiona first noticed there was a problem with her son when he was just four days old, in February 2008:
"He was jaundiced, but I thought that it would clear up within a few days as a lot of babies are jaundiced after birth.
Two weeks later he was still jaundiced, so I started to get worried. At his eight week check up his stomach was so swollen too that his belly button had been pushed outwards, but the GP just told me to put him in the window to get some more sunlight.
"When I showed the doctor his stomach he said that it was normal for his belly button to be stuck out."
Daniel's health continued to deteriorate and when he was 12 weeks old his condition was diagnosed as biliary atresia.
Daniel underwent an operation immediately to try and redirect the bile through his liver, but it wasn't a success.
"His liver had already been too badly damaged for the operation to work. If he had been diagnosed earlier when his symptoms first became apparent then he would probably only have needed the first operation," explains Fiona.
"But by the time it was carried out the surgeons told us that it was too badly damaged. His only chance of survival was a liver transplant."
Daniel was put onto the transplant list for seven months, but as the months went by, no donor liver could be found.
Daniel's condition started to worsen and the doctors approached David to see if he would consider donating part of his own liver to save his son.
"After two months of being on the transplant list, there was no donor to be found and Daniel started to get worse, which was terrifying. We knew that a liver transplant was the only way of saving him," says Fiona.
"When the doctors asked David if he would be a donor, he didn't hesitate. Luckily he proved to be a good match for Daniel, which meant that the transplant could go ahead.
I was worried about both my son and my husband being in the operating theatre at the same time, and it was a risky decision for David to make, but it was Daniel's only chance of survival and he didn't hesitate to save him.
The transplant took place in December 2008 and David, who works in pharmaceuticals, was taken down first to the operating theatre.
"I walked down with David first, then I had to carry Daniel down a short while later," says Fiona.
"It was a nerve-wracking wait whilst the operations took place and I just had to pray that everything would be alright."
A fifth of his David's liver was taken out and transplanted into Daniel and the operation was a success.
"I had to run between the hospital wards after the operation and I would feel guilty leaving one to go and see the other," says Fiona.
But just a couple of days after the operation, David was well enough to walk down the corridor and come and see Daniel. It was a very emotional moment, knowing that he had saved his son's life.
David took two months to recover before he went back to work, but Daniel suffered constant infections and potential rejection for the next two years and was in hospital.
"We had a constant worry that the liver was going to be rejected and he was constantly having to go back into hospital for treatment, but now it finally seems to have settled down and he is doing well," says Fiona.
"He has to go for check ups every two months now, and he has just started nursery school in September. I am so grateful to David - he has given our son a second chance at life."
For more information on biliary atresia visit Childsliverdisease.org.