Tomorrow marks a special day for the Duke and Duchess of Cambridge.

Prince William and Kate will celebrate daughter Princess Charlotte’s first birthday.

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It’s likely William, Kate, Prince George and Princess Charlotte will spend the day privately with closest family and friends.

The Duke and Duchess are expected to hold the festivities at their country home Anmer Hall in Norfolk, where they have raised Charlotte and two-year-old George.

This photo of Prince George with his baby sister Princess Charlotte got the world swooning.

It’s understood they want a relaxed, intimate birthday party following the busy schedule the Cambridges have been keeping.

They have just returned from a royal tour of India and Bhutan and have been celebrating the Queen’s 90th birthday.

Likely guests at Charlotte’s party include Kate’s parents Carole and Michael Middleton, her sister Pippa and her brother James.

Royal sources say Kate is planning the “most adorable” party.

Nursery rhymes are a possible theme for the event. Carole owns Party Pieces with her husband and is fond of Beatrix Potter themes for children’s events. Peter Rabbit could well make an appearance at Charlotte’s get together.

She was named Charlotte Elizabeth Diana in tribute to her grandmother Diana, Princess of Wales and her great-grandmother the Queen.

Charlotte’s privacy has been carefully guarded by her parents Prince William and Kate and she has only been seen in public on one other occasion, her christening.

With AAP