“Whenever we filmed him, whenever I spoke to him, he really wasn’t interested in who he was, the Prince part was probably the least important part.”

He added: “His naval career was hugely important, his role as a father was hugely important.

“But also probably his biggest role was sort of, as consort and support to the Queen.”

He continued: “This was a guy that was born into service and he was born in a Royal Family.

“He went through military service and what you learn in this documentary is that service was at his absolute core.”

Mr Bullen said that the Duke “wanted to continue with his naval career” but when Elizabeth became Queen at such a young age, the Duke had “taken a vow of service.”

He added: “The greatest service he could do to his country was to support his monarch.”

On the day prior to their wedding, the King granted Philip the style of His Royal Highness.

The couple welcomed four children during their marriage.

Their eldest, Prince Charles, is first in line to succeed Queen Elizabeth II.

Following the death of the Duke last year, the BBC aired a royal documentary called Prince Philip: The Royal Family Remembers. The programme featured royal interviews filmed both before and after the Duke’s death.

Speaking in the documentary, Camilla, Duchess of Cornwall, spoke fondly of the Duke’s role alongside the Queen.

The Duchess said: “I saw the way he supported the Queen.

“Not in a flashy sort of way, but just by doing it quietly. Following along behind.

Aside from his royal duties alongside the Queen, the Duke carved out his own path within the Royal Family, particularly through his Duke of Edinburgh scheme.

The youth awards programme focusing on self-improvement exercises was founded in 1956 in the UK and has since expanded to 144 nations.

Each year, the Duke of Edinburgh scheme inspires hundreds of thousands of young people, from all walks of life, to explore who they are, grow in confidence, and expand on skills that they need to navigate successfully through life.