The headteacher of a prestigious grammar school in Buckinghamshire has been asked to stay away from the school while it investigates claims he took cocaine and smoked cannabis he confiscated from pupils.

Tim Dingle, head of the Royal grammar school, has categorically denied the allegations of drug-taking which were made by a 35-year-old woman who claimed they had a three-year affair after meeting over the internet.

Nicky Barr claimed in the Daily Mail that Mr Dingle, aged 46, had pretended to be a 34-year-old surgeon called Dr James Banyard who was single and due to inherit the Vernon pools empire.

Ms Barr said she only discovered his real job, and the fact he was married with a daughter, after finding a conference badge printed with the name “Tim Dingle, Royal grammar school, High Wycombe”.

Mr Dingle has not returned to the school since the drug allegations were published but has strenuously denied them.

Andrew Higginson, chairman of governors, has written to parents stating:

“In accordance with the procedures for undertaking such an investigation, I have written to Tim Dingle requiring him to stay away from school while an investigation takes place.

“I would stress that requiring Tim to stay away from school does not constitute disciplinary action, nor is it a presumption of guilt.

“Indeed, the investigation affords Tim the opportunity of having his voice heard.”

The school’s governors have taken advice from Buckinghamshire council and appointed an independent investigator to look into the allegations. A report is expected early next month.

Mr Dingle was due to leave the school at Easter to become head of the private St George’s college in Buenos Aires, Argentina. The bilingual school said its governors would also be examining the allegations “with caution and firmness”.

Roy Page, senior deputy headteacher, was due to take over as head of the Royal grammar school at Easter and has been placed in charge temporarily while the investigation is carried out.

Mr Page said it was inappropriate for him to comment on “gossip” or the ongoing investigation.

Thames Valley Police said it would not be investigating the allegations of drug-taking as it had not received any complaint of criminal activity.

Mr Dingle has spoken out in the past against the Government’s decision to downgrade cannabis to a class C drug saying it sent the wrong message to pupils.

He has also been quoted in The TES criticising the Government’s handling of the funding crisis in 2003, during which he pledged pound;15,000 of his salary over five years to ease his school’s budget problems.

The Royal grammar school has consistently performed at the top of national league tables for GCSE results and was used as the set for the Channel 4 series That’ll Teach ‘Em in which teenagers were given a taste of 1950s, then 1960s, education.