Happy sixth birthday Princess Charlotte!

A photograph of a very happy Princess Charlotte has been released to mark her sixth birthday.

The picture was taken by her mother the Duchess of Cambridge, at her family home in Norfolk where she is celebrating today.

Princess Charlotte is the great-granddaughter of the Queen and is fourth in line to the throne.

She was born at St Mary's Hospital in Paddington, central London on 2 May 2015, weighing 8lb 3oz.

Princess Charlotte is the second child of the Duke and Duchess of Cambridge - Prince William and his wife Catherine

In this new birthday portrait, Charlotte is pictured outdoors wearing a pretty dark blue short-sleeved dress with little flowers on.

For her last birthday, her parents released a picture of the Princess volunteering with the rest of the family, by helping to deliver meals to elderly and vulnerable people living near to one of the Queen's homes in Sandringham, Norfolk.

The young royal delivering to those in need

The Duchess of Cambridge is a very keen photographer and it has become tradition for her to release photos she has taken on her children's birthdays.

This photo of Princess Charlotte was taken by her mother on her second birthday

Another photo Catherine took was also released earlier this year, showing the Queen and the Duke of Edinburgh with their great-grandchildren, including Charlotte.

Here Princess Charlotte is sitting with her great-grandparents, her brothers, Prince George and Prince Louis and her cousins

When Charlotte was just a baby, the Duchess also released a picture of the little royal being cuddled by her big brother Prince George.

The future King giving his little sister a kiss

Scroll down to send in your happy birthday messages for Princess Charlotte below