A teacher has been left traumatised after his identity was confused with a convicted drugs offender.

Gareth Thomas taught English at the Archbishop's School in Canterbury for seven years.

But he was left stunned when he couldn't return to the profession after taking a career break in 2007.

The reason was the Criminal Records Bureau (CRB) found his details closely matched those of a man convicted and jailed for a drugs offence in Winchester 29 years ago.

The mix-up has left 58-year-old Mr Thomas, of Sturry Road, jobless and undergoing treatment for stress.

It is a double blow for Mr Thomas, who volunteered to work at Canterbury Prison as a Spanish translator and found his application blocked by the same case of mistaken identity back in 1995.

Now Mr Thomas feels his life and career have been blighted.

He said: "My details are being confused with those of a criminal and this has been going on for 15 years.

"This could happen to absolutely anybody."

Mr Thomas was on a Return to Teaching course at Christ Church University in January he applied to be a supply teacher at his old school, Archbishop's.

He believes this latest CRB alert was triggered because his namesake has reoffended.

But having been cleared in 1981 of any association with the offender, he was asked to undergo fingerprinting to establish his innocence again.

Mr Thomas said: "If the CRB is confusing me with a criminal it could work vice versa.

"They say it is for the safety of children, but no one is safe in this system."

Michael Liddecoat, head teacher at Archbishop's School said although he had a copy of a police letter confirming Mr Thomas' innocence, he still had to go through the process of submitting an online CRB check and that there was no provision on the form to indicate Mr Thomas' history.

He said: "A fingerprint check was proposed as the solution so that the potential for a clash could be permanently removed.

"I think it is most uncommon and it is a situation I have never experienced previously."

Although the CRB check on Mr Thomas was requested in February he has yet to receive official clearance and Mr Liddecoat said: "I am unable under the regulations to employ someone without a CRB check."

In the meantime Mr Thomas has been forced to claim benefit and he feels like his life has been turned upside down by the experience.

He said: "I have exhausted all my funds and I feel that by having to prove I'm not someone else I've been thrown out of my own life."

A spokesman for the CRB, who refused to be named, said once Mr Thomas had asked for a new CRB check and been given a reference number, he should have contacted the bureau himself to explain his position.

• The Criminal Records Bureau has since investigated the situation and apologised to Mr Thomas for a number of errors in the processing of the check. It has paid compensation for difficulties caused.