The royal photographer, who remarked that both Harry and his wife know how much the Queen values the Commonwealth, highlighted that Duchess Meghan is "evidently no fan" of it.
"Harry should stop listening to his wife, who is obviously filling him full of these ideas. She is evidently no fan of Her Majesty’s beloved Commonwealth," he wrote.
"Indeed, after the Commonwealth service at Westminster Abbey in March — her and Harry’s last official royal engagement — Meghan couldn’t wait to leave."
According to Arthur, whilst Harry stayed and spent the evening with the Queen and the rest of the Royal Family, Meghan went straight to Heathrow Airport, "where British Airways staff held up the last flight to Vancouver so she could get on."
As the respective President and Vice President of the Queen’s Commonwealth Trust charity, Harry and Meghan have played an active role since their appointment, but Arthur remarked that Harry's remarks will "tarnish its reputation", particularly among young people and in doing so will concern the Queen.
The royal photographer re-called past experiences of Harry's when he represented the royals whilst visiting Commonwealth countries.
"He hugged the Jamaican Prime Minister, ran races with Usain Bolt and, in his blue suede shoes, danced with kids in the clubs," Arthur recalled.
"He knew just how important this organisation is to his grandmother. How quickly he forgets."
Since annoucing they will no longer be senior members of the Royal Family, Harry and Meghan have moved to LA and are currently staying in Tyler Perry's mansion with their one-year-old son Archie.
The couple are hoping to work in public speaking and focus on the official launch of their foundation, Archewell, that plans to focus on the many social justic initiatives they support.