Jimmy's is special. The Leeds hospital is one of only three centres in England where children can receive new livers.

In Lennox Nicholson's case, his parents were told that their five-month-old son was so ill that only a transplant could save him.

Yesterday, surgeons told the family that a suitable liver was available and received the go-ahead for a ten-hour operation.

Steve Pollard, the consultant surgeon who is clinical director of the paediatric transplant team at Jimmy's, explained just how challenging and intricate such an operation can be.

"Children are particularly complex because the vessels are so small and the fluid balance going in and out of their bodies is much more critical than in adults," said Mr Pollard, who was one of the surgeons assisting yesterday.

"Children are often a lot sicker than the adults we see."

To complicate matters further, not only was a little boy in the operating theatre yesterday, but an unnamed women patient who received part of the donated liver.

"There were actually three simultaneous operations going on at once in adjacent operating theatres," said Mr Pollard.

"We had a paediatric transplant, an adult transplant and the division of the donated liver, which takes two to three hours in itself," he said.

Dividing the donated organ to give life to two people is time-consuming and tricky, with no room for error.

"You have to dissect out the vessels and bile duct taking care not to make the surface bleed, then you have to individually clip and tie all of the vessels."

The right lobe of the liver, the larger part, went into the adult. The left lobe, the smaller portion, went into Lennox.

The new liver had to be inserted so vessels were lined-up for connection.

The next stage was ensuring the "plumbing" was secure and all veins, arteries and ducts connected properly.

"You follow a set sequence when you remove the old liver and that same sequence has to be followed in reverse as you connect up the new vessel."

For the fine "plumbing" job, consultant paediatric transplant surgeon Mark Stringer wore powerful magnifying glasses.

Around him were up to a dozen surgeons, nurses, anaesthetists and technicians. In the next operating theatre, transplant surgeon Giles Toogood, a former Worcestershire cricketer, connected the new liver to his unconscious adult patient.

Hospital officials say the next 24 to 48 hours will be crucial to judge whether the operation has been a success.

Organ rejection, often a problem with hearts, is not such a problem with livers, although Lennox will have to stay on anti-rejection immuno-suppressant drugs for the rest of his life.

Now all Mr Pollard and his colleagues can do is hope that their patient makes a good recovery.

Mr Pollard said: "What we must not forget is that this was only possible because of the generosity of the donor's family. We rely on the good will of people at this difficult time."

He urged everyone to consider joining the national organ register and to discuss the issue with your nearest and dearest.