Profiteers or keeping the lights on? The power plants that make millions a day

Concerns over whether gas generators are making fair profits are prompting fresh proposals to reform the system

Travel 18 miles north of London and the grey bulk of a gas power plant comes into view near Rye House railway station in Hertfordshire.

Rye House power station has generated electricity since 1993, making it Britain's longest-serving such power plant still in the market. But it also produces some of the most expensive electricity in the country.