The vaccine has got a terrific record over the years Sir Liam Donaldson

He's calling for parents to be offered individual jabs: "For the moment there is doubt and where there is doubt further investigation is required and until that time that it is resolved scientifically, then the parents absolutely deserve the choice."

Autism was first diagnosed in the 1940s. It is a disorder which affects a child's ability to relate to other people and can lead to anti-social behaviour.

Dr Wakefield's theory is that the triple vaccine damages the gut, triggering inflammatory bowel disease which allows dangerous toxins to seep out into the bloodstream and up to the brain, triggering autism.

The biggest scientific study to date has been carried out in Finland where around two million children were tracked for 14 years. No link was found between MMR and autism.

Janice Ballard has an autistic son, Jamie. He had his MMR jab after being diagnosed as autistic.

Mrs Ballard says it is a difficult condition: "His behaviour can be quite distressing sometimes with head banging and hand biting.

"It takes a while to come to understand how he is and if he wants to do something, it's very difficult to channel him into other directions. He's absolutely obsessed with doing that thing."

Sir Liam says: "The vaccine has got a terrific record over the years. It's been in operation around the world for decades.

"Millions of children have been vaccinated and hundreds of thousands of lives have been saved.

"We've looked carefully at Wakefield's claims. He's a lone voice but nevertheless we haven't ignored him, but we can't substantiate his claims."

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