Accounts for Saudi Arabian-owned LSRM Holdings last year reveal the Harrow-based group fell £3.7m into the red, coming on top of losses of £2.2m in 2019 and £14.5m in 2018.
Revenue rose by 7% to £134m.
Over the year headcount was reduced by around 100 to 763 as the business was streamlined to meet Covid operational challenges. To support furloughed workers the group received £1.15m in Government support.
Among the key trading arms, the main M&E business Lorne Stewart improved on last year even in the face of Covid, recording a £350,000 loss on revenue up 12% at £131m, compared to a £690,000 loss in 2019.
But the much smaller Rotary Building Services suffered a £2.3m loss on revenue slightly dipped at £9.5m.