In an interview for his local paper the Peterborough Telegraph, Mustard said he had at first assumed that the official-looking envelope waiting when he returned from a dive-trip to Galapagos was a tax bill, and he had left it unopened it for a while.

“It's definitely one of those letters you read two or three times,” he told the paper. “You think it's a friend sending it as a joke. Because I'm a photographer, I enter photography competitions and I'm used to winning awards. But all the awards I have won I entered to win, and with this I had no idea.

“This is bigger than all of the other awards. It's an incredible shock but a very happy one."

Mustard, 43, had met the Queen and the Duke of Edinburgh 15 years ago when he guided them round an exhibition in Estonia in which his work had featured.

“She was quite a keen photographer and was quite interested in how I get the photos,” he said.

The photographer has not only won major awards in the most prestigious wildlife competitions, including the GDT European, NHM and BBC Wildlife Photographer of the Year, but set up the international Underwater Photographer of the Year competition. Attracting huge entries from the start, it quickly became one of the major events on the calendar.

His books such as Secrets of the Seas and Underwater Photography Masterclass, as well as articles and regular workshops, have inspired countless divers to embark on and develop their own underwater photography, as illustrated in a recent article by Henley Spiers on Divernet.

Alex Mustard also revealed the true nature of the vehicle cargo of popular Red Sea wreck the Thistlegorm in a Diver article in 2014, following an exhaustive research and photography project.

Divernet - The Biggest Online Resource for Scuba Divers