Fellow contractor Balfour Beatty also said on Tuesday it was to write off £100m associated with its investment in Metronet, largely to be offset by gains on other ventures.

The exceptional costs on the project of £121.3m pulled WS Atkins into a full-year pre-tax loss of £39.6m although underlying profits of £81.7m showed 19 per cent growth as the other areas of the group’s business performed well.

Metronet is currently in limbo, unable to access lending facilities pending agreement between the shareholding companies and banks.

The company last week called in Chris Bolt, arbiter of the 30-year, £30bn Underground public-private partnership, to attribute responsibility for the overrun. The review will take up to nine months. The arbiter may all-o-cate additional costs to con-tractors, including Atkins.

Given those uncertainties, Atkins has taken an exceptional loss of £91.3m, comprising £70m of equity investment and £21.3m of earlier-year profits. There is also a £30m cash impact from losses from station refurbishment in the London Underground project.

In April the company said it expected the full-year exceptional loss in respect of Metronet to be £36m. 

Asked if he regretted entering the venture, Keith Clarke, chief executive, said: “We are where we are.”

Atkins also announced it would sell its UK-based property service operation Lambert Smith Hampton to a consortium of management and the Bank of Scotland. The deal is worth £40m in cash plus £6.5m in vendor loan notes. A further £10m could be payable later, depending on LSH’s performance this year.

Atkins’s revenue for the year increased 20 per cent to £1.26bn. Other rail activities benefited from a recovery in workload. The biggest division, design and engineering, saw revenues rise 18 per cent. The board recommended a final dividend of 14p, taking the total to 20p.

Balfour Beatty said its Metronet write-off would be largely offset by an exceptional gain of £50m on the sale of its 24.5 per cent interest in Devonport Dockyard and a £40m gain resulting from the crystallisation of tax losses in the US.

Shares in Atkins fell 33p to £10.97 while shares in Balfour Beatty closed up 31⁄2p at 4443⁄4p on Tuesday.