French energy giant EDF was the big winner among Network Rail's suppliers, scooping almost £300m in the last financial year through providing Britain's track operator with electricity.
EDF's contracts accounted for 5.4 per cent of the Government-backed group's £5bn budget for 12 months. Building firm Costain, which has been working on the revamp of London's Farringdon Station, was the next best-paid, although it earned more than a third less than EDF at £184.5m.
The figures back the argument that power supply is among the greatest costs for big business at a time when there are fears over an energy gap. They also show how lucrative work with Network Rail can be. Eleven companies – including construction group Balfour Beatty and engineer Atkins – earned more than £100m.
Network Rail is the single biggest electricity customer in the UK. EDF won a 10-year contract in January to supply it with energy from its eight British nuclear power stations in a deal that will see three-quarters of Britain's trains run by electricity rather than diesel by 2020.
The French giant has still to agree terms with the Government over building a new plant at Hinkley Point but EDF chief executive Vincent de Rivaz said the Network Rail deal was a "huge vote of confidence" in nuclear.
Although the Government sees building nuclear power stations as vital, they can suffer unusual difficulties. EDF said last week that seaweed forced it to take nine reactors offline at its Torness facility near Edinburgh, where the electricity supply was previously interrupted by jellyfish.