LONDON (AP) — Prince William and his wife, Kate, have released three new photographs of Princess Charlotte to mark her fourth birthday.

Kensington Palace said the photos were taken by Kate, the Duchess of Cambridge, in April at Kensington Palace in London and at the family's country home in Norfolk.

Charlotte, who turned 4 Thursday, is the royal couple's middle child, between 5-year-old Prince George and 1-year-old Prince Louis.

She is fourth in the line of succession for the British throne, after her grandfather, Prince Charles; her father, William; and her brother George.

Prince Harry and his wife Meghan, who are awaiting the birth of their first child, wished their niece a happy birthday on Instagram. Responding to a Kensington Palace post featuring Charlotte's photos, they wrote: "Happy Birthday Charlotte! Lots of love, H and M xo."