Prince Charles has played his part in helping rail become more environment-friendly.

The Prince travelled in the EWS-operated Royal Train to Scarborough, hauled by a Class 67 locomotive fuelled by 100 per cent bio-fuel.

The loco, named ‘Royal Sovereign’, was powered by waste vegetable oil which would otherwise have been dumped by the food industry.

EWS said the run up the East Coast main line reduced CO2 emissions by 19 per cent.

The Prince, who was effectively taking part in an experiment, became the first passenger in Britain to be hauled by a locomotive using 100 per cent bio-fuel.

EWS described the journey, which covered 900 miles overall, as a big success. “This was a very rigorous test on the East Coast main line during a busy time,” said spokesman Graham Meiklejohn.

“It was a realistic trial involving stops and starts and travelling at a peak time.

“The whole trip was monitored by our engineers, who are analysing the trial.

“This trip has proved that it works but obviously there are discussions to be had about the fuel duty issue. It costs a lot more than red diesel.”

The journey formed part of a four-month programme of testing to assess the suitability of bio-fuel for mainline services.

EWS has worked closely with the Royal Household as part of its continuing work to lower the amount of carbon emitted from transportation to royal engagements.

If the trial results prove positive, it will assist in the decision-making over the Royal Train being powered by 100 per cent bio-fuel.

The trial follows testing by EWS to assess the impact various blends of bio-diesel would have on the locomotive. These tests concluded that 100 per cent bio-diesel could be used for main line operations.

The fuel used met the European EN 14214 standard and is produced from selected waste vegetable oil derived from rapeseed or sunflower cooking oil.

Importantly, it does not contain palm or other hydrogenated oils commonly found in other fuels.

Keith Heller, EWS chief executive, said: “This trial was a major step forward in evaluating the suitability of bio diesel for the UK rail industry.”