A Whistleblowing tax inspector who claimed businessmen were deliberately overtaxed by his colleagues so that they could boost their pay packets, has dramatically lost his tribunal case.

Alun Curtis, who worked at Trinity House, in Oxford, alleged HM Revenue and Customs officials unfairly charged traders too much tax to make it look as if they had successfully solved cases to qualify for performance-related pay.

The 55-year-old used Public Interest Disclosure legislation to expose the alleged practice where additional money was obtained from inquires into traders’ tax returns.

An employment tribunal took place at Reading earlier this month.

The inspector, who has worked for the HMRC since 1979, believed there was potentially “hundreds of thousands of pounds” which had been illicitly extracted from unsuspecting businessmen.

However, Mr Curtis, of Merton Way, in Yarnton, lost his case in a reserved judgement published yesterday.

The employment tribunal panel ruled his allegation of “corruption” within the workforce was unfounded.

Instead they focused on his own motivation for gaining a top rating from his Personal Development Evaluation (PDE), thus him qualifying himself for a two-and-a-half per cent pay rise.

Mr Curtis had previously argued during the three-day hearing that it was unfair he was handed a “good rating” when he believed he deserved better.

“We find that the claimant has no real reasonable basis for making this allegation,” the statement read.

“The repeated reference to PDE entitlement is a powerful indication of the claimant’s true frame of mind.”

Mr Curtis had suffered a number of health problems and has not been at work at the Oxford tax office since June last year.

The judgement added: “We are confident that once he has put behind him the matters which led to this hearing, he will still have much to contribute to the public service.”