Why Prince Charles' visit had the MasterChef Australia judges quaking

'We were so nervous!'

For the first time in MasterChef Australia history, Prince Charles and his wife Camilla will make a guest appearance on the cooking show this week.

And while you'd expect the contestants to be nervous having to plate up a dish fit for royalty, it was judges Matt Preston, Gary Mehigan and George Calombaris, who were feeling the pressure.

"We were all very nervous," Matt reveals of having the heir to the British throne on their show. "It was one of those pinch-yourself moments."

Gary Mehigan, Matt Preston, Prince Charles and George Calombaris.

Despite being nervous, Matt says Prince Charles, 69, was an absolute delight.

"He was funny and a bit cheeky and asked us what kind of judges we were, so it was a great experience," Matt, 54, says.

"He couldn't have been more generous to all the contestants. And it was also great to be doing the reception at the Royal Flying Doctor Services, which is such an iconic way that people overseas see Australia."

Prince Charles is a keen foodie, and wanted Indigenous and local ingredients used in the challenge for contestants.

As a result, the contestants had to cook for 150 guests, including His Royal Highness, at the Royal Flying Doctor Service base in Darwin, Northern Territory.

Each team was required to make a minimum of four types of canapé: one savoury, one vegetarian, one gluten-free and one halal. Some of the menu items included wallaby tartare and quandong chutney.

"One of the great things about Prince Charles, is that he has a 40-year history with sustainability and organic, farming food," Matt explains.

"He wanted us to show him local and seasonal produce. He knows his stuff."

This week is Royals Week on MasterChef Australia. Tune in on Wednesday, July 4 at 7:30pm to see the contestants cook for the Prince of Wales and the Duchess of Cornwall.