Prince Charles and Camilla
Prince Charles and Camilla Parker Bowles made the most expensive royal trip. Pictured: Prince Charles, Camilla arrive on the second day of the Royal Ascot horse racing meet, in Ascot, west of London, on June 20, 2018. Getty Images/Daniel Leal-Olivas

Prince Charles and Camilla Parker Bowles' tour in South Asia is the most expensive trip made by a member of the royal family this year.

The Duke and Duchess of Cornwall used a luxury RAF aircraft when they visited South Asia. It ended with a travel bill that was more than three times higher than a similar trip taken by Prince William and Kate Middleton, The Times reported.

In 2016, the Duke and Duchess of Cambridge visited India on a British Airways flights before using private jets for a shorter internal journey. Their total travel bill was $140,828.

Meanwhile, the Prince of Wales' and his wife travel to India with their entourage in October on an RAF Voyager which has been refitted for diplomatic travel. It costs them a whooping $13,075,660. Prince Charles and Camilla visited Malaysia, Brunei and Singapore and returned with $81,263 travel bill.

According to the publication, it is the most expensive trip undertaken by the royal in that year to April. However, the Buckingham Palace defended Prince Charles' choice of using the RAF aircraft.

"The Prince of Wales is representing Her Majesty, therefore, it is important in terms of representation that the form of transport is appropriate but at the same time justified in terms of value for money," the palace said. "We are using the same aircraft that the prime minister or foreign secretary would be using for a similar visit."

The report also noted that Prince Charles used the royal train seven times that costs about $26,151 per journey. On the other hand, Queen Elizabeth II only used it three times.

In related news, Prince Charles and Camilla just visited Salisbury after the poisoning attack. The town suffered from a slump in tourism after the incident and the royals were hoping to turn that around with some positive PR from their visit.

Meanwhile, Camilla confessed that she loves gardening and would love to do it every day if given the chance. In fact, she prefers it over royal duties.

"I'd be out in my garden all day, every day if I were allowed. I love to get my hands dirty," the duchess said.