Kate Middleton

Kate MiddletonGetty: Images

The Duchess of Cambridge celebrated her 40th birthday on the 9th of January

The Duchess of Cambridge took to Twitter yesterday to send thanks to her many well-wishers on her 40th birthday.

While Kate Middleton is one of the most recognizable faces in the United Kingdom, a milestone birthday such as this offers the chance to reflect on her role in the Royal Family.

The Duchess of Cambridge entered public life as a shy recent graduate but has transitioned into a confident and hard-working member of the Royal Family.

To mark the occasion, the Duchess of Cambridge released 3 portrait photos.

The images were taken at Kew Gardens back in November and will form part of a project from the National Portrait Gallery where the duchess is patron. They will go on display in three locations that she has chosen, including Berkshire, where she spent the majority of her childhood, St Andrews, where she went to university and began her relationship with her husband, and Anglesey, where the couple lived together just before and in the early part of their marriage.

The photos will be housed in the permanent collection of the National Portrait Gallery.

The photos were taken by Pablo Roversi.

The Duchess of Cambridge made sure to thank her fans for the thousands of birthday wishes she received.

Kate's 40's will bring several more changes to the life of the Duchess as her public work will continue to grow and evolve.