Kate Middleton’s brother admits he has his suspicions about Prince William, while the couple was still courting one another.

The Princess of Wales, who married the Prince in 2011, had to face hiccups from brother James Middleton.

In his new book serialised by the Mail, James reveals: “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.”

Meanwhile, 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.