Here she tells the BBC what happened.

"Katie had a very unremarkable viral infection.

She had slipped into a coma, and never regained consciousness

Audrey Harrington

"The doctor diagnosed flu and told me to give her aspirin four-hourly, which I did.

"She had about four aspirin over the course of about a couple of days.

"She seemed to get better and she was talking about returning to school. But the following day she was nauseous and she started vomiting.

"First of all, very faintly, then the vomiting became relentless.

"I called the doctor and eventually Katie was admitted to the local hospital in Chelmsford, and there she was diagnosed as having encephalitis or meningitis.

'Very sick'

"The she was admitted to Great Ormond Street Children's Hospital.

"By that stage, she was a very sick little girl.

"She had slipped into a coma, and never regained consciousness.

"She died in Great Ormond Street four days after she had been admitted.

"Doctors there, within an hour, diagnosed she had Reye's syndrome.

"Reye's syndrome is an illness that follows the onset of a very ordinary viral infection.

"The child seems to recover, and then starts to vomit. The liver breaks down and the brain starts to swell, and it's the brain swelling that's devastating, overwhelming complication.

"As long as doctors can keep the brain swelling down, then the child can hopefully make a good recovery because the liver can restore itself within about a month.

"It's this awful brain swelling which overwhelms the child.

'Loath to give drugs'

"My other child Nicky, who is two years younger, was ill at the same time.

"She had an ear infection, and was really rather poorly.

"She was given antibiotics and I was told to give her aspirin, but I'm very loath to give my children drugs, so I wouldn't give Nicky two lots of medication.

"She didn't have aspirin and she was fine.

"Katie had had aspirin before. only in therapeutic doses, and it was when she was in Great Ormond Street that we were asked if she was given aspirin.

"We were told that in America, studies had shown a link between aspirin and the onset of Reye's syndrome.

"Following Katie's death, we made inquiries and contacted the US embassy.

"We found that there was an organisation in the US that supported families that had had Reye's syndrome.

"It was there that we discovered the Surgeon General in the US, two years before Katie had died, had issued a warning that children and teenagers up to 19 should not be given aspirin for flu or chicken pox."