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Why Kate Middleton returned to London with the children minus Prince William

Happy birthday Louis!

Ainhoa Barcelona

The Cambridges have returned to London ahead of the start of the school term on Wednesday, but one family member was notably missing, Prince William. The Duke had to fly out on Tuesday morning – the day of Prince Louis' first birthday – to travel to New Zealand for an official visit. William bid farewell to his wife Kate and their three kids as he prepared for his two-day trip, which follows last month's tragic Christchurch mosque shootings.

The palace said the trip will see William "pay tribute to the extraordinary compassion and solidarity that the people of New Zealand have displayed in recent weeks". The Duke, who is visiting on behalf of his grandmother the Queen, will begin his trip in Auckland followed by a day in Christchurch to meet with survivors, first responders and families affected by the attacks.

Prince Louis turned one on Tuesday

It's understood that the Cambridges held an early, private celebration for little Louis so that William could be in attendance. And on the day of Louis' actual birthday, Kate will have been making sure her children George, five, and Charlotte, three, were all packed and ready for their first day back at school. George attends Thomas's Battersea while Charlotte is a pupil at Willocks Nursery School.

MORE: Why Duchess Kate and Zara Tindall curtsied differently to the Queen

The royals spent the children's Easter holidays at their country house, Anmer Hall, in Norfolk and were spotted enjoying a day out with the Tindalls last week. William and Kate also spent Easter Sunday with the Queen and other members of the royal family in Windsor.

A look back at Prince Louis' christening:

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To celebrate Louis' big day, William and Kate chose to share three delightful photos of their baby boy playing in the garden at Anmer Hall. In two of the portraits, Louis' rosy cheeks match his red jumper, which is covered in bits of greenery as he mucks about in the moss. The third picture sees Louis looking precious in a blue jumper with a dog motif.

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