A school wasted £100,000 by paying over the odds for building work, a council auditor has found.

Wimbledon College did not get a range of quotes for the work and ended up paying a “considerably higher” than market price to a contractor it used frequently, a surveyor who investigated the blunder said.

An account of the incident published last month by Merton Council said their surveyor found the school had not complied with asbestos and building control regulations – although the council now says there is no evidence that was the case.

An internal audit report presented to the council’s general purposes committee said the Edge Hill secondary school paid £516,543 for the work in 2009 and 2010, which included improvements to heating systems in the school’s art block and canteen and a new entrance to the school.

A committee member later said the total was about £100,000 above the going rate, and the school had failed to follow its own financial guidelines.

The audit report said: “A surveyor from the council’s facilities section carried out a sample check of five invoices and concluded that the amount charged was considerably higher than expected.”

A council spokesman said the school, which is run by a Jesuit foundation but receives advice from the council, is a Grade II listed building and so cheaper quotes might not have been best value.

But they also said: “Some procedures for commissioning work were not followed, and these were flagged up with the school who agreed to follow more robust procedures in the future.”

The school’s headteacher at the time the work was carried out left this summer, although the move is not believed to be related to the overpayment.

The overspend is the second mismanagement of a school project in Merton.

In September, the Wimbledon Guardian revealed Mitcham’s Stanford Primary School had paid £190,000 to a contractor who produced fake invoices, giving the false impression the school had shopped around to get the best price for building work.

Auditors estimated the school had paid £100,000 more than it needed to for the 68 projects undertaken by the builder. A fraud investigation was launched by the police, but no one was prosecuted over the incidents.

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