The deal will see 20,000 mainly private sector contracts passed to British Gas along with 400 gas and electricity engineers who specialise in the installation, service and maintenance of commercial gas boilers and electrical systems.

Kanat Emiroglu, managing director of British Gas Business, said “This acquisition gives us the platform that is needed to rapidly build a complete energy solutions business.

“It accelerates our growth strategy in the business energy services market, which is expected to be worth £2 billion by 2015.”

He added: “It is great news for the people at Connaught, its customers and for British Gas Business’s existing customers.”

British Gas will also take over Connaught’s training academy in South Wales.

British Gas Business’ aims to build a complete energy solutions business for its 750,000 customers.

In the last two years alone, the arm has bought five firms operating in the energy services and management sector.

These include BMSi, Semplice Energy, Energy and Building Management Solutions and Newnova Group which have seen British Gas Business take on 5,100 new jobs in insulation, smart metering and energy efficiency.