The contract will be worth around £2bn and will create 3,000 construction jobs.

The O’Rourke jv fought off fierce competition from rival bidder Balfour Beatty/Vinci in one of the most keenly contested contract races for years.

The Enquirer first revealed in January that O’Rourke was winning the race for the job.

The firm will be delighted to win the contract now its work on the London 2012 Olympics is coming to an end.

The Hinkley job is subject to planning consent and EDF Energy comitting the cash.

Construction will involve the main civils works for the nuclear island, the conventional island and supporting structures.

The O’Rourke team has entered into a preliminary agreement for Early Contractor Involvement which will see it working on the development of the detailed design, construction methodology and programme.

The ECI arrangement means engagement can begin early with the local community and supply chain.

This contract is the first relating to the main construction works which will see up to 25,000 jobs created on site over the course of the project, including an estimated 400 apprenticeships for the civils work.

EDF Energy Chief Executive Vincent de Rivaz said: “I am delighted to welcome Bouygues TP/Laing O’Rourke Joint Venture into our project.

“The agreements announced today show we are continuing to maintain momentum in 2012 towards our final investment decision.

“We will work with Bouygues TP/Laing O’Rourke Joint Venture over the next few months to ensure we are in the best possible position to begin work on site once the investment framework and permissions are in place.

“This was a close, very competitive tender which attracted some high quality and robustly-costed bids.  We look forward to harnessing the relevant and complementary experience, expertise and knowledge offered by this powerful partnership of two well-respected and highly-committed construction companies.

“So much has been achieved on site already and we now have a strong partner in Bouygues TP/Laing O’Rourke Joint Venture to help to plan the next phase of works. For us, early engagement with key contractors is critical to ensure that they are clear on their responsibilities and the expectations we have of them.

“The civils contract will assist the UK’s economic recovery and boost economic prospects and prosperity locally. Our project will inject billions of pounds into the economy, revitalise entire sectors of industry and support tens of thousands of further jobs.

“2012 is a defining year for new nuclear. We will continue our discussions with Government about agreeing a legally robust investment framework.

“Agreeing the contract for difference is key – as I said at the recent Energy and Environment Select Committee hearing – it means that we and Government will have to be clear about our costs before we sign a contract for our project.

“It’s part of the open and transparent process taking us towards our final investment decision. The final investment decision will be based on cost evidence which will be robust.

“We are also working towards obtaining crucial decisions on planning consent and design approval later this year. A huge amount remains to be done but we are determined to do it.”

Ray O’Rourke, Laing O’Rourke Chairman and Chief Executive said: “We are delighted, along with our partner Bouygues Construction, to be appointed by EDF Energy as preferred bidder to lead the development of the first new nuclear power station, which is vital to meet the UK’s future energy demands and support the wider economic recovery.

“Today’s announcement marks an important juncture in Laing O’Rourke’s growth and development as a delivery partner of choice to the power sector.

“We look forward to bringing this nationally strategic project into successful reality. Through our direct delivery capability and investment in a new generation of engineering jobs and skills, we have the opportunity to create a valuable legacy that is so critical to the future success of the UK nuclear industry.”

Philippe Bonnave, Deputy CEO of Bouygues Construction, said: “We are very proud to be preferred bidder in partnership with Laing O’Rourke. This project confirms the mutual confidence that exists between EDF, Laing O’Rourke and Bouygues Construction.”

SCALE OF THE CONTRACT

The scope of work of the main civils contract includes the Nuclear Island, Conventional Island, Balance of Plant, Waste Disposal, Operational Service Centre; Temporary Civil Structures, Contractor’s offices on site; Contractors roads, platforms and networks.

The scale of the work involves sufficient steel reinforcement to build up to 9 HMS Illustrious aircraft carriers and enough left over to build 5 London Eyes; each nuclear island is the equivalent size of St Paul’s Cathedral; and around enough concrete will be poured to fill Twickenham Rugby Stadium to roof level.