Prince William had to go through 'compatibility scrutiny' from Kate Middleton's brother

During their initial meetings, Prince William was "put through his paces" by Kate Middleton’s brother, James Middleton, who had a unique approach. 

Although James knew Prince William well, he arranged several sit-down meetings to evaluate whether William was truly deserving of his sister. According to James, after six years of dating, he tested his future brother-in-law thoroughly, and William was "pining" during these meetings, though not for Kate herself.

In his upcoming autobiography, "Meet Ella," which will be released on September 26, James reveals that Prince William had to "earn my trust."

He wrote, serialised by the Mail: "By now, William has been dating Catherine for six years, so I know him well. But I remember putting him through his paces when we first met. Did he deserve my sister? He had to earn my trust.

"It helped of course that William was so genuinely fond of Ella. When he first encountered her as a tiny puppy at Bucklebury, he was smitten. He’d had a black Labrador, Widgeon, as a boy, and when Widgeon died, he left an empty space. I felt William was pining for a dog when Ella was around."

Their fairytale romance did not begin immediately, with the pair initially friends after meeting at St Andrews university, The Mirror previously reported. But it was at a catwalk show for charity that the Prince found himself head over heels for Kate.

Ingrid Seward of Majesty magazine revealed: "Kate and William's relationship began as a friendship, but when Kate did that catwalk show, that was the first time he really looked at her as more than a lovely friend. Early dates were very simple.

"They used to go to a place called Ma Bells and they would be very discreet. Often William would turn up and Kate would appear later but they wouldn't be together. William wanted to keep it under wraps as long as he could. They shared an apartment together in their second year and that’s where their relationship moved up a pace."