Over the next few years utility companies will plough billions of pounds into underground cabling and sewage projects.

New tunnelling operations director, Stephen Meadowcroft said the sector was a potentially lucrative field for Costain because there were relatively few rival civil engineering contractors with big tunnelling capability in the UK.

He said: “There aren’t many companies that have that expertise. Having tunnelling in our armoury is a strength.”

In order to ensure that the power networks can continue to deliver Britain’s energy needs in the future extensive new infrastructure will need to be built over the coming years.

Already Costain has won £200m worth of tunnelling contracts in London for National Grid to house power lines as part of a major replacement programme over the next decade.

Work is due to start by the end of this year on the London Cable Replacement Tunnel, which will run 33km across the capital from Hackney in the east to Willesden in the west, via Kensal Green and then on to Wimbledon in south west London..

Mike Napier, strategy and business development director for infrastructure, said: “Many of the underground high-voltage cables serving our large cities are nearing the end of their lives.

“Digging up main routes into London to replace them would cause severe disruption so tunnelling under the capital is the most effective way to secure our energy supply for future generations.”

Also, the Government’s planned construction of a new generation of nuclear power stations, as well as new coal and wind-power stations, will need to be connected to the UK’s power network.

“The output from them is going to be very much greater so, in crude terms, they need more cables to link in to the national grid,” said Napier.

They will also require tunnels to dispose of cooling water out to sea.

Costain has recently completed a contract in West Ham, London to remove the threat of sewer flooding to several hundred homes and work is nearly 50% completed on 11km of tunnels to bring the wastewater treatment of the Brighton area up to modern standards.