Workers at Tory donor’s JCB factory test positive for drugs after sniffer dogs called in

The JCB group employs 8,000 people in the UK across its factories in Staffordshire, Derbyshire and Wrexham. Photograph: Paul Rapson/Alamy

JCB, one of the UK’s biggest manufacturers, is investigating a spate of drug use among workers based at its headquarters and has sacked a “significant” number of staff, the Guardian can reveal.

A message sent to UK employees last week by the digger-maker’s group human resources director, Max Jeffery, seen by the Guardian, said it had been conducting a “series of investigations into substance misuse” over the past two months. This had resulted in a “small but significant number of people leaving JCB”.