One of the biggest waste-management companies in the South-East has been fined £1million for its illegal treatment of dangerous material including asbestos at its depot in Harlesden in a landmark court case.

Powerday Plc stored 14,500 tonnes of the hazardous waste at its base in Scrubs Lane, after transferring it from a power station in Nottinghamshire.

The company also moved around 3,000 tonnes of non-hazardous trommel fines originating from the Harlesden site to another Aylesbury Mushroom Farms Ltd in Oxfordshire.

Powerday Plc admitted the offences but told Harrow Crown Court it had a permit that allowed it to legally store more than 10 tonnes of certain types of hazardous waste at the Harlesden site.

However the Environment Agency denied the claim and the court ruled in its favour.

The first incident in Harlesden occurred in 2010 and the second two years later.

The company and its managing director apologised to the court for the historic failures adding it had since corrected and improved its systems and procedures.

In addition to the fine, the company agreed to pay the Environment Agency’s prosecution costs of £243,955.35.

The case was the first ever where a company has been convicted of a number of offences involving the receipt and storage of large quantities of hazardous waste.

Four other offenders, including the owner Aylesbury Mushroom Farms, had been previously sentenced for offences relating to the same operation at Oxford Crown Court.