David and Samantha Cameron did an "extraordinary" job of caring for their disabled son while carrying on professional lives, his doctor said today.

Dr Mando Watson, who looked after Ivan Cameron for five years, heaped praise on the "strong couple" and said Ivan had been "deeply" loved.

The praise comes as shadow chancellor George Osborne said the Camerons had received thousands of emails of support from members of the public.

Dr Watson said: "They are remarkable people.

"In my career I've always been astonished at how parents manage to cope with very difficult circumstances but what David and Samantha have been able to do is to bring a child up in the most wonderful way and continue with very sophisticated professional lives as well.

"I do think that is an extraordinary achievement."

Dr Watson, 46, has been a consultant paediatrician at St Mary's Hospital in Paddington, west London, since 2001.

She declined to say whether she was with six-year-old Ivan when he died on Wednesday morning just 45 minutes after being admitted to the hospital.

She said such deaths were still a shock to families, even when they knew their child would die young.

"I think there are many families who live with this constant worry that the next emergency may be the last one.

"I think this is a very frequent problem in these families who have children with very severe health problems.

"It's always extremely difficult. However well prepared you are it's a very difficult moment.

"David and Samantha did know that he was very disabled, they did know that his life was going to be very limited and I think they were as prepared as any parent could be."

Dr Watson, who is Greek, said the Camerons were going through a very difficult time but would come out the other side.

She added: "There are lots of other families who've been through what they've been through and actually parents do pull through," she said.

"David and Samantha looked after him and managed to cope with all the difficulties of looking after him incredibly well.

"They are a very strong couple and they will remain strong, I'm sure of that. But I think it's a very difficult time."

Ivan was born with Ohtahara Syndrome, which left him with very severe epilepsy, complex disabilities and cerebral palsy.

"He was very limited in what he was able to do and had seizures very frequently," Dr Watson said.

"For some children with this disability, the seizures are there on a daily basis and they can be very difficult to control."

Medication could help control seizures to a degree but not all the time, she added.

"What we're looking at is children who are very profoundly disabled, they aren't able to feed and they are dependent on tube feeds with tubes going into the stomach.

"They aren't able to walk or move about and they aren't able to communicate verbally.

"So they have extremely limited abilities but at the same time they are actually able to respond and show love and affection and enjoy the love and affection that they receive from the people around them.

"In many ways, it's a very warm and rich life."

Dr Watson said Ivan was able to smile and people got a sense that he was a happy child.

"Ivan was a really lovely boy, he was very beautiful," she said.

"He had an extraordinary presence and really drew people to him.

"There were a lot of people who really loved him deeply and at times he was able to give a wonderful smile that was so heart-warming.

"Sometimes he wasn't smiling so much but you still got a sense of him feeling happy and that was really wonderful.”