Kate Middleton's brother James expecting first child with wife Alizee Thevenet

Kate Middleton is set to become an aunt again as her brother James is expecting his first child with wife Alizee Thevenet. 

The Princess of Wales's brother shared the delightful news on his Instagram on Wednesday, announcing that he and his wife Alizée are expecting their first child together.

In the snap, Alizée is seen cradling her bump, as the couple's dog Mable appears rather excited about the coming arrival.

James Middleton, the brother of the Princess of Wales, wrote: "We couldn’t be more excited … well Mable might be."

He continued: "It was a very difficult start to the year after losing my beloved Ella however we will end the year with the most precious little addition to our growing family."

Congratulatory messages have already begun rolling in, with TV presenter Ben Fogle leading the way, with a simple "Congratulations".

Another commenter added: "Huge congratulations to you both!!" while a third wrote: "Omg congratulations! I’m expecting too and the baby will be here at the end of the year as well. Good luck to us both"

A fourth sweet added: "What fabulous heartwarming news to share! Wishing you all well and happy times."