The deal will also realise £7.5m in net profit in the current financial year and cut future contributions to the fund, which previously had an estimated £56m shortfall.

In a short trading statement, Costain said a recent spate of contract wins had secured £700m in revenue for 2011 and bolstered forward orders to £2.4bn.

In the last few months, Costain has picked up a 10-year framework deal for nuclear decommissioning, a £200m tunneling job for National Grid, London Underground’s Bond Street Station upgrade and a major sewage treatment works jobs at Frankley for Severn Trent.

Costain is also preferred bidder on around £400m of projects.

Improvements in trading leave Costain with cash in excess of £100m and no significant borrowings.