Prince William was a "fantastic support" to the Middleton family in their early days of fame

He told The Sunday Times: "William was a fantastic support for us as a family. He did everything he could to protect us from the intense interest, not just in Catherine, but also her immediate family. But at that time I was already in a vulnerable state of mind and it was an added pressure."

James - who is now married to Alizée Thevenet and has son Inigo, 11 months, with her - was then asked to give a Bible reading at the wedding of William and Catherine - which was televised and received an audience of 162 million viewers from around the world - and recalled that it was such an "honour" that his sister had asked him to do it in the first place, although he noted that the anticipation was just like any other family wedding he has been to.

He said: "I'd never seen a royal wedding.

"There hadn't been one in my lifetime. Not a big one anyway. I wasn't aware of the scale or the global interest. I just felt privileged that my sister was asking me to do it, and it meant something to her. I wanted to make sure I did it. Really, the build-up to Catherine's wedding was no different to Pippa's or other friends' weddings."