The Royal Family are standing by Prince Charles in the face of allegations of hypocrisy.

Prince Charles travelled to Cambridge University to speak with scientists at the university’s Whittle Laboratory. The purpose of the visit? To discuss ways to lower aircraft emissions.

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A noble enough intention. But eyebrows were raised when it was revealed that Prince Charles travelled from Highgrove to Cambridge by way of a private helicopter. The 100-mile trip is estimated to have cost $20,000.

Clarence House defended the Prince of Wales’ transportation method in a statement published by Yahoo! News.

“The prince is not personally involved in decisions around his transportation arrangements, though he ensures all carbon emissions are offset every year,” a spokesperson said. “They are made based on what is possible within the constraints of time, distance, and security.

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“In order for him to undertake as many engagements as he does across the U.K. and around the world, he sometimes has to fly,” the spokesperson added. “As he has often said, as soon as there is a more sustainable way of making these journeys, he’ll be the first to use it.”

Last year, BBC News determined that Prince Charles was the highest spender on transport, with his annual costs totalling more than $1.7 million.