Sophie held her shirt up with no number and told the girls: “I’m much younger.”

The Duke continued to be amused by the number on the back of his shirt and he said: “Even I know there aren’t that many people on the field.”

The royal couple watched girls from four Leeds schools go through rugby training drills and chatted to them – asking about how they got into the sport and how their current season was going.

Edward and Sophie also met two pioneers of women’s rugby league – Julia Lee, the UK’s first female Rugby League referee, and Lisa McIntosh, a former Great Britain rugby league captain who was the first woman of colour to skipper a British sports team.

Both are involved in a project to ensure the story of the first generation of female rugby league players is heard more widely and they showed the royals around the exhibition of the history of women’s rugby league.

Later, the couple attended a community sport and recreation awards ceremony, where the Duchess paid a sweet tribute to her husband during a speech, with Edward looking visibly moved.

The Duchess of Edinburgh said her husband is “the best of fathers, the most loving of husbands and he is still my best friend” and “I am so proud of the man he is”.

They both wiped away tears after she described how, like his father, the late Prince Phillip, “my husband never seeks compliments for himself”.

She said: “Which is why I am grateful for this chance to able to publicly celebrate and compliment him.”

Sophie said Edward was “so happy and humbled” when the late Queen made him a Knight of the Garter in 2006, and “equally delighted and moved” when the new King – “who we are both incredibly proud to support” – made him Duke of Edinburgh.

She told the audience on Friday: “Both he deserves in equal measure, and I am so proud of the man he is.

“He is the best of fathers, the most loving of husbands and he is still my best friend.”

Elsewhere in her speech, Sophie said Edward has been her guide, and added: “Whatever he is doing he gives 150% of himself, and if all else fails he gives any energy he has left out to our exhausted dogs or laying waste to the garden.”

Wiping away tears again, the duchess ended her speech saying: “So, here’s to you my darling Edward and may I, along with all your family and so many friends, and so many others wish you the happiest of birthdays.”

After Sophie’s speech, the couple were pictured in a sweet moment together as they embraced.

Later, the duke was surprised with a birthday cake, which he cut after the guests at the awards lunch sang Happy Birthday and cheered.

The duke laughed along with the audience when, as Happy Birthday rang out, the guests all came to a collective halt over what to call him in the “happy birthday dear…”  section.