William, Prince of Wales tried his best to playing cards with the "ruthless" Middleton family

In his book 'Meet Ella: The Dog Who Saved My Life', published in the Daily Mail, James wrote: "William would flinch at our ruthless determination to win at all costs. He'd be delighted to be the first out, and when no longer compelled to take part, he'd slink off to cuddle [my dog] Ella.

"Better still, he'd absent himself from the game entirely. 'James, does Ella need a walk?' he'd ask before we'd even started dealing the cards.

"My sisters and I would exchange a knowing glance. William, for all the competitive rigour of his military training, was happy to be a loser at cards."

In the book, James opens up about his mental health struggles and credits his dog Ella with helping him through some dark moments.

He revealed he pushed his loved ones - including his sisters Catherine and Pippa - away when he was at his lowest.

James wrote: "I contemplate ways of dying so I can get off the giddy roller-coaster that is sending me to the brink of madness. I cannot sleep because my mind is in tumult.

"The insomnia is dizzying. I am utterly exhausted. I feel misunderstood; a complete failure. I wouldn't wish the sense of worthlessness and desperation, the isolation and loneliness, on my worst enemy. I think I'm going crazy.

"Yet I know I am privileged; fortunate, too, to have a loving and close-knit family - Mum and Dad, my sisters Catherine and Pippa, their husbands William and James - but I push them all away.

"I do not answer their phone calls. Emails remain ignored. Invitations to visit go unheeded. I hide behind a double-locked door, unreachable."

He then recalled that it was his beloved black spaniel who would save him time and time again.

James added: "I haul myself back from the brink, slowly climb down the ladder and stroke Ella's silky head. She is the reason I do not take that fatal leap. She is Ella, the dog who saved my life."