William and Kate
The Duke and the Duchess of Cambridge.

Prince William and Kate Middleton joined the New Year's Eve party hosted by Pippa Middleton in her parents' back garden in Berkshire, it has been reported.

The Duke and the Duchess of Cambridge joined the revellers at the teepee-style tent, known as a "kata", the Daily Mail has said quoting eye-witnesses in the village.

The royal couple reportedly shared jovial moments at the party. A villager described William as wearing a flat cap and green Barbour jacket, according to the paper.

The royal pair were initially expected to celebrate their first New Year as man and wife with the Prince of Wales and the Duchess of Cornwall in Scotland.

Prince Harry, however, did not attend Pippa's party. Harry was partying with friends and Princesses Beatrice and Eugenie at a ski resort in Switzerland on the New Year's Eve, the ABC News has reported.

Pippa, 28, Kate's party planner sister, works for London-based events firm Table T.