Three companies have been fined a total of more than £1 million after workers were exposed to asbestos during the refurbishment of a school.

Balfour Beatty Regional Construction was fined £500,000 and paid £32,000 in costs after admitting it breached safety rules during work at St Mary's Church of England Primary in Walthamstow in 2012.

NPS London Ltd also admitted it broke the law, was fined £370,000 and paid £32,000 in costs, while Squibb Group Ltd, was fined £400,000 and £175,000 costs after it was found guilty of breaching rules at trial.

Three classes and 18 staff at St Mary's were moved from their original school site in The Drive to renovated space at the former Warwick School building in Brooke Road in September 2011.

However, the toxic fibre was not discovered to be present in the building until further work took place during the 2012 school summer holidays.

Southwark Crown Court heard that on July 24, 2012, a worker removed part of a suspended ceiling in one refurbished room and identified suspected asbestos.

Asbestos fibres were subsequently found in numerous areas in the school.

The court heard Waltham Forest Council had a contract with NPS London to manage development and refurbishment of its estate. 

NPS London is a joint venture between Norse Group and Waltham Forest Council and council leader, Clare Coghill, sat on its board as a director from 2014 until she resigned only last month. 

At the time of the incident, the principal contractor for the work was Mansell Construction Services, which later became Balfour Beatty, with Squibb Group working as a sub-contractor. 

A Health and Safety Executive (HSE) investigation found that although an asbestos survey was completed, multiple other caveats and disclaimers were not appropriately checked.

Speaking after the hearing, HSE inspector Sarah Robinson said: “The principal contractor and contractors on site did not review the survey report in detail, and did not take into consideration the multitude of caveats.

“Therefore the work undertaken did not adopt the high standards of control expected for working where there was the potential to expose workers to asbestos.”

An initial HSE report into the incident in August 2012 had warned there was a “high probability” construction workers had been exposed to the toxic material.

The report also stated some school staff and cleaners may also have been exposed to small amounts of asbestos.