Carillion wins £600m of new work in Oman and Northern Ireland

The deals cap a first half of the year that has seen total orders, and probable orders, worth £2.5 billion.

The company, with its city centre headquarters overlooking Ring Road St Marks, has seen services work – looking after buildings rather than constructing them – grow to account for nearly two thirds of its operating profits.

Carillion said it was still assessing the impact of the Brexit vote. The company has little work on the Continent, with most of its operations in the UK, the Middle East and Canada. It employs around 46,000 people, 21,000 of them in the UK and around 400 in Wolverhampton.

In its trading update to the City, the company said: "The referendum vote in favour of the UK leaving the European Union has obviously created uncertainty for the UK economy as a whole and therefore for businesses generally, including Carillion, and it is clearly too early to predict the extent to which businesses will be impacted by this result.

"However, Carillion has no significant operations in Mainland Europe and prior to the referendum we undertook extensive work to assess the possible impact on our business of a vote to leave and we have put in place robust plans to manage this outcome."

Meanwhile the boost in services work over recent months is set to increase first half revenue.

The two new deals are a £240m, four-and-half year support services contract for Petroleum Development Oman (PDO) and two support services contracts for the Northern Ireland Housing Executive that have an initial value of £60m, but are potentially worth up to £366m over 10 years.

Carillion chief executive Richard Howson said: ''We are delighted to have secured the contract extension for PDO that reflects the strong partnership we have developed with PDO. It also reinforces our commitment to supporting PDO through the efficient management and operation of its critical infrastructure, using our sector leading ability to provide facilities management services to the oil and gas sector across the Middle East, including operating in the challenging desert environment where the vast majority of PDO's assets are located.

"We are also delighted to have been awarded two important new contracts for the Northern Ireland Housing Executive, which build on the strong relationship we have developed with the Housing Executive for whom we have provided services for many years."

The value of Carillion's order book, plus probable orders, at the half year stage is around £17.4 billion – the same level as in December.

Carillion's success in with Public Private Partnership (PPP) projects has seen it seal financial deals on four new projects and it has been selected as a preferred bidder for fifth. It is currently working on the £350m Midland Metropolitan Hospital in Smethwick, under one of the Government's new PF2 private finance deals.

It is also carrying out the major Paradise Circus building project in Birmingham city centre and says construction work in the Middle East, UK and Canada is "performing in line with expectations".