Now is the time to make that decision. Not when you're sitting in the intensive care unit of a hospital. So say the parents of Martin Burton... and they should know. As their son lay on a life support machine, they had to make the most difficult decision of their lives – whether to donate his organs to save other critically ill patients. But, as they tell Jennifer Scott, it is a choice they've never regretted

Talking about it, you'd think, would be the last thing Sue Burton would want to do.

Even now it all feels too raw, too recent to her – that horrific night in August 2003, when her 16-year-old son Martin collapsed from a massive brain haemorrhage and fell into a coma from which he never awoke.

Yet, as she speaks, her voice is calm, each word a building block, firmly placed, constructing a vivid likeness of her noisy, loveable son. Amid the pristine cream leather sofas and dove-coloured carpets of Sue's Grantham living room, you get a sense of the boisterous boy who once lived here.

Turning to the photo album she has compiled, which offers a tiny flick-book of Martin's short life, she radiates maternal pride.

"The photos used to make me cry but now they make me laugh," she says.

You can see why. Each one brims with personality... the cheeky grin, the incorrigible teenage swagger, the scruffy jeans, and the hole in the sock.

The pictures range from Martin's "official" school portrait (his blonde hair combed into place with a lick and a promise) to one showing him with his arms casually slung around two girls, giving a thumbs-up to the camera.

"That's Martin," smiles Sue, pointing gently, while her husband Nigel nods in agreement.

"He looks quite a character," I say. His mum rolls her eyes, fondly."That's what all his teachers used to say."

His popularity, always apparent during his life, became more so following his death. As he lay on life-support in Nottingham's QMC, an endless stream of teenagers snaked down the corridors to say their goodbyes.

At the crematorium, his parents found teddies wearing jumpers that read: "Best mate.""One of his friends wrote this joke out for him," says Sue. "It turned out they'd got a detention for laughing at it in school."Yet he wasn't merely the class clown. At school perhaps not academic like his older brother Chris ("they were like chalk and cheese but very close all the same," says Sue), he had long harboured ambitions to be a nurse.

"He was a caring sort," says Sue. "If anybody was in trouble, he was always right there for them."

These memories of Martin's kind-hearted nature helped steer Sue through the hardest decision of her life – whether to donate his organs to help others.

The night he was rushed to hospital, Sue and Martin were alone in the house.

Husband Nigel, then in the RAF, was working in Las Vegas and Chris was staying with his girlfriend.

At about 2am, Sue was lying in bed when she heard a crash from Martin's room and he came staggering into her bedroom. "He collapsed in front of me," she says, her voice quiet, containing the emotion. "I couldn't rouse him, so I rang an ambulance."

Martin had suffered a massive brain haemorrhage. Initially rushed to hospital in Grantham, he was transferred to the QMC at 5am.

By that time, his brain haemorrhage, which it turned out resulted from a congenital condition, was too extensive for doctors to save him.

"By breakfast, we were told he wasn't going to make it," says Sue.

Martin suffered from a condition which his parents still struggle to express in medical terms."They call it an arterio-venous malformation," says Sue which, Nigel explains, means a lack of blood-carrying capillaries starved his brain of the nutrients it needed, resulting in a sudden "short circuit".

She agonised for a long time after her son's death."I was convinced for a long time that, as his mother, I should have noticed something but a long chat with the consultant eventually convinced me there would have been no signs."

As Martin lay brain-dead, on life support, Nigel faced an agonising 30-hour journey home, while Sue sat numbly in the QMC's intensive care unit.

It was then she was approached by a consultant and asked if she had ever considered donating Martin's organs.

Sue immediately consented.

"There was no question in my mind when I was put on the spot at that terrible time," she says. "What happened was going to happen whatever decision we made. We were going to lose our son."

Martin's heart, lungs, kidneys, liver and corneas were all donated.

I ask if her decision brings her comfort, fearing the question sounds trite for no matter how precious the gift, there can be no easy consolations in such circumstances.

"No – I wouldn't say it gives me comfort," she replies slowly, as if trying to clarify her feelings. "But it's a decision I've never regretted. It's something positive that's come out of his death."

"Although we never discussed organ donation with Martin, we feel it's what he would have wanted."

Martin's liver saved a man with a young family; his lungs went to an elderly gentleman; one kidney to another elderly man; the other to an elderly woman. His corneas have been frozen.

And his heart went to a 15-year-old boy who had been given only hours to live.

Sue initially wrestled with this knowledge, finding it difficult to accept that another family had what she wanted so badly – a healthy teenage son.

Donor families are allowed limited contact with organ recipients via their transplant co-ordinators – if both parties are agreeable.

In this way, Sue and the mother of the boy exchanged letters and photos of their sons and she could see visible evidence of the life Martin had given to another.

"There's an element of consolation in the fact that Martin saved another child's life and spared some other parents going through what we went through," she says.

In the bleak days after Martin's death, Nigel and Sue became involved with an organisation called the Donor Family Network, which they'd heard about via the transplant co-ordinator.

Many of the families in the network have also lost relatives and they band together to support new members and raise awareness of organ donation.

Nigel is DFN's vice-chairman and he and Sue tour freshers' fairs and shopping precincts, trying to get people to think about the subject.

The fact they speak from experience makes the stranger on the street give weight to their words.

"Now's the time to make that decision," Nigel urges. "Not when you're sitting in the intensive care unit of a hospital."

The Government recently outlined plans to double the number of transplant co-ordinators to try to boost the number of donations. A more controversial option "presumed consent" – in which everyone is considered a donor unless they opt out – has not been adopted.

Nigel and Sue welcome the plans.

"I don't think presumed consent is the way to go," Sue says.

"I spoke to a couple of mums of children who had liver transplants and they said however desperate you are for the organ, it's very difficult to accept it because it means somebody else has lost someone. The only way they could accept it was by knowing that it was a gift, freely given."

As Sue steels herself for what would have been Martin's 21st birthday next month, she knows the suddenness of his death and shock it caused will always be with her. "Somebody described the loss of a child as being like a gaping wound that in time becomes a scar. The scar is there forever," she says.

But it is in the telling of Martin's story that Sue draws and offers comfort.

Through the network, she has been put in touch with recently bereaved families and uses her experience to counsel and comfort them on the telephone.

"I can say, 'You won't always feel as you do now'," she says. "But it doesn't mean you'll ever accept it. It's not the natural order of things – to lose your child."

Nowadays, she can speak of Martin warmly, remembering good things. Like any mum, she is fiercely proud of him.

His school has created a prize in his memory."It's given to the pupil who has done the most to support fellow students.

"It seems very appropriate."

Indeed it does. Helping others to live, after all, is Martin's legacy.

To register as a donor see www.uktransplant.org.uk/ukt/how_to_

become_a_donor/registration/consent.jsp. For the Donor Family Network, see www.donorfamilynetwork.co.uk or call 0845 680 1954.