The company’s auditor Grant Thornton has told the engineering group that it has wrongly accounted for earnings from a number of defence contracts within its Chesterfield Special Cylinders (CSC) division by reporting the figures up front rather than over the life of the contract. This has led to a £1.2m increase in operating losses.

The mid-tier firm has been auditor of Pressure Technologies since 2018 following a competitive tender and has been responsible for the audits.