'Besotted': Kate Middleton and Prince William's adorable new addition

Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge, are reportedly new parents - to a puppy cocker spaniel. Photo / Getty Images

Prince William and Kate Middleton have a new little addition to their family.

The Duke and Duchess of Cambridge were devastated after the death of their beloved dog Lupo two months ago, but the royal pair and their three children George, Charlotte and Louis are reportedly now "besotted" with a new cocker spaniel.

The Mail on Sunday reports the Cambridges were gifted the 8-month old black spaniel by Kate's brother, James Middleton, before Lupo's death.

Kate and Will's new pet is Lupo's niece or nephew, after James bred a litter of six puppies last year.

James, 33, and his fiancee Alizee Thevenet, 31, posted pictures of the puppies on Instagram in July, revealing after 56 days of nurturing the little ones, he was about to send them all to their forever homes.

He also had his own spaniels in some of the adorable pictures; Ella, Inca, Luna and Zulu, and their golden retriever, Mabel.

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James originally gave Lupo to the Duchess for Christmas in 2011 from a litter of puppies he had bred that year.

In November, the Duke and Duchess confirmed via Instagram that Lupo had died.

"Very sadly last weekend our dear dog, Lupo, passed away. He has been at the heart of our family for the past nine years and we will miss him so much. – W & C."

Lupo was so important to the family that Prince William referenced the pet in his first official interview after becoming a father in 2013.

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He said: "For me, Catherine, and now little George, are my priorities. And Lupo.

"He's coping all right, actually.

"As a lot of people know who have got dogs and are bringing a newborn back, they take a little bit of time to adapt, but no, he's been all right so far."