Wills' anniversary gift to Kate

Prince William is set to present Duchess Catherine will some of his late mother's jewels to celebrate their first wedding anniversary later this month.

The British royal proposed to the then Kate Middleton is 2010 with Princess Diana's sapphire engagement ring, but sources close to the prince say he will add to this by presenting Catherine with another priceless heirloom at the end of the month.

Prince William and Kate Middleton at the Foundation Polo Challenge, June 2011. Source: Getty.

A royal insider told In Touch magazine: "I expect William will definitely give Catherine more jewellery. Very likely a piece from Princess Diana’s extensive private collection.”

After he proposed, William revealed the decision to give Catherine his mother's ring was in order to "keep her close!"

Kate Middleton received Princess Diana's ring for her engagement. Source: Getty.

He explained "It is a family ring. It's my mother's engagement ring so I thought it was quite nice because obviously she's not going to be around to share any of the fun and excitement of it all - this was my way of keeping her close to it all.

"I had been carrying it around with me in my rucksack for about three weeks before that and I literally would not let it go, everywhere I went I was keeping hold of it because I knew this thing, if it disappeared I would be in a lot of trouble and because I'd planned it, it went fine.

"You hear a lot of horror stories about proposing and things going horribly wrong - it went really, really well and I was really pleased she said yes."