Carillion’s order book will hit £20bn for the first six months of 2008.

In a trading update, it said contract wins such as the £300m Olympic Media Centre, a £330m deal at Heathrow Terminal 5 and £700m of work in the Middle East pushed up orders from £15.8bn in the same period last year.

It said the integration of Alfred McAlpine would mean cost savings would reach £40m a year by 2009, higher than the £30m previously forecast.