Campaigners reacted with concern after a retired teacher was told by a judge he was blameless for downloading 7,466 child porn images.

Former deputy headteacher Phillip Carmichael admitted downloading the indecent pictures and videos — but blamed drugs he took to control his Parkinson's illness for giving him "uncontrollable" sexual urges.

The married 58-year-old, a former teacher at Wantage County Primary School, was given an absolute discharge at Oxford Crown Court after being told he was not responsible for his actions.

It means the court did not want to punish him — a decision branded "surprising" by child protection campaigners and unprecedented by law experts.

Henry James, prosecuting, said the images included 730 rated at the second-most graphic level four, plus one at the most serious level five — which can include pictures of sadism and bestiality involving children.

Carmichael was arrested after police raided his home in Adkin Way, Wantage, last September, as part of a Europe-wide investigation into child porn websites.

Carmichael was traced after sending an email to one website complaining about the quality of the images he had received.

Roger Harrison, defending, said: "It is a tragic case. This gentleman had a 27-year teaching career which was impeccable in every way."

He said Carmichael was prescribed Cabergoline and Ropinirole — known as dopamine agonists — from June 2002 to help control his Parkinson's Disease.

Mr Harrison said experts believed the drugs could cause compulsive behaviour, known as impulse control disorders, including gambling, shopping and the repetitive use of machines such as computers.

He said: "The defendant, when the drugs were prescribed, received no warning whatever.

"The central submission in this case was that it was not his fault."

Sentencing him, Judge Mary Jane Mowat said: "This is a wholly exceptional and very distressing case.

"To say that he was to blame would be a complete denial of the reality. He was not only an ill man at the time, but a man whose medication can be regarded as wholly responsible for the commitment of these offences."

Judge Mowat said Carmichael was automatically required to sign the sex offenders' register, but made no order banning him from working with children.

Claude Knights, director of Kidscape, said Carmichael should have sought medical help when he first noticed his behaviour change as a result of the drug.

She said: "Whatever the circumstances we could never condone the downloading of this many images.

"It is surprising and disappointing that this has been taken fully as a mitigating circumstance.

"It was over 7,000 images. It was a repetitive thing."