Profit for the year ended 31 July before tax and an exceptional net pension gain of £18.2m in 2007 rose to £38.8m from £32.4m a year earlier on revenue up 46% to £656.7m.

The firm said future prospects were underpinned by a forward order book of £2.1bn and bidding pipeline of £2.2bn.

"Given the defensive nature of the group's activities, we have been relatively untouched by the recent turmoil in financial markets and the upheaval elsewhere in the economy," said chief executive Richard Cuthbert.

"The outlook for our growing and increasingly diverse business remains promising and we are confident that the group will continue to prosper in line with our long term plans."