"He is determined to get his travelling costs down," a senior courtier tells Mandrake. "Obviously there will be occasions when his security team will advise him against this, but he has told us that his default position from now on will be to turn right when he enters an aircraft. He is acutely aware that this is no time for ostentatious expenditure."

When the 26-year-old prince flew off to Courchevel for a skiing holiday with his girlfriend Kate Middleton and her family earlier this month, it went unreported that the second in line to the throne sat among the economy passengers on the British Airways Heathrow to Geneva flight. "There was a security presence, but it was all very low-key and William sat with Kate, her sister Pippa and a group of friends among the other passengers," the courtier adds.

"I think a lot of people on the flight didn't even realise who they were. William actually hates having a fuss made of him when he travels and said that he found it a lot more relaxing than having the cabin crew all nervously hovering around him at the front of the aircraft."

Michael and Carole Middleton, Kate's parents, elected, interestingly, to travel business class on the flight, but this may have been because Mrs Middleton was entitled to an upgrade with her husband since she is a former BA employee.

This was believed to be the first occasion that the prince had sat in economy, but, even so, the trip garnered some unwelcome headlines for him because he had to break into his 16-month course at the Defence Helicopter Flying School – funded by the taxpayer to the tune of £800,000 – to take the holiday.

Prince William's decision to switch from business and first to economy – a policy that has also been adoped by a great many businesses lately – contrasts with Gordon Brown's increasingly grandiose travel arrangements.

Earlier this month I disclosed how, when the Prime Minister returned from his trip to Washington, his British Airways flight was permitted to taxi directly to Royal Suite One, which is normally reserved for the Queen and senior members of the Royal Family.

A British Airways captain got in touch after the story appeared to tell me that Brown's flight was also accorded the call sign Speedbird One which is considered highly pretentious in aviation circles and was eschewed even by the status-conscious Tony Blair when he travelled as prime minister.

Both BA and Clarence House declined to comment on Prince William's travelling arrangements.

by:telegraph