[attach id=261417 size="medium"]The Duke and The Duchess of Cambridge on an open-top vehicle as they depart from Henderson Airport, Honiara, Solomon Islands, during the nine-day royal tour of the Far East and South Pacific in honour of the Queen's Diamond Jubilee in September. Photo: Danny Lawson/PA Wire[/attach]

The Duke of Cambridge celebrates his 31st birthday tomorrow.

William has had a momentous 12 months with his wife Kate becoming pregnant and the baby due in mid-July.

The royal couple’s baby will be delivered naturally at the private Lindo wing of St Mary’s Hospital in Paddington – where the Duke was also born.

Other highlights of the past year include William and Kate’s successful tour of the Far East and south Pacific last autumn to mark the Queen’s Diamond Jubilee.

St James’s Palace said the “Duke of Cambridge will be spending his birthday privately”.

The second-in-line to the throne is likely to celebrate his milestone with friends ahead of the wedding this weekend of close friend Thomas van Straubenzee and Lady Melissa Percy, the Duke of Northumberland’s second daughter.

The groom is a long-time friend of both William and Harry, and the Royal brothers were at the chartered surveyor’s London stag do earlier this month.

The wedding is being held on Saturday in a parish church close to the Duke of Northumberland’s ancestral home in Alnwick near Newcastle.

Kate could miss out on the celebrations as there are less than four weeks to go to the birth of her baby.

William and Kate do not know their baby’s gender and want it to be a surprise when he or she is born.

A source said: “The Duke and Duchess do not know the sex of their baby and they’ve decided not to find out beforehand.”