He might be a member of the British royal family but that doesn't mean Prince Harry is above flying commercial like the rest of us.

The new dad was spotted by an eagle-eyed royal fan on a flight from Rome back to London following his trip to Italy for the Sentebale ISPS Handa Polo Cup.

Amy Garrick shared photos of the Prince on Facebook that were re-posted to Instagram, revealing she had noticed the Prince was on her flight while waiting to use the plane's bathroom.

A passenger said the prince looked worn out. Photo / Supplied

"As I'm standing there, I look over and see a guy who looks like Prince Harry. And he has a wedding ring on and looks very tired," she wrote.

"The guy next to him looks like security and is glaring at me. Finally my brain clicks and I realise, it is Prince Harry on the way back to London from Rome."

Ms Garrick wrote that Harry "politely smiled and said hi when he realised I knew who he was".

"I tried to get a photo as he got off the plane. I didn't want to harass him and felt bad taking one, but it isn't every day you see him!" she continued.

Harry was in Rome to take part in the fundraising polo match, which raises money for his Sentabale charity.

It was the first royal engagement for the Prince since he welcomed the birth of his son, Archie Harrison, with wife Meghan Markle earlier this month.

Despite being royal, Harry isn't opposed to flying on commercial airlines, with the Duke and Duchess of Sussex reportedly spotted on a British Airways flight to Nice, France, shortly before their wedding.

The Duke of Sussex Prince Harry attends the 2019 Sentebale ISPS Handa Polo Cup at Roma Polo Club on May 24. Photo / Getty Images

According to Vogue, the royal family can charter a private jet if the engagement is state sanctioned, in the same way other government officials would fly by charter.

However, the younger members of the royal family do appear to try and cut costs by going commercial when they can for public engagements.

Kate Middleton flew on a commercial flight for a solo visit to the Netherland and she and her husband Prince William also used an airline to flight to Los Angeles for an official visit.