Kate Middleton, Prince William send crowd wild with their surprise move

Prince William and his wife Kate Middleton surprised fans with their unannounced appearance ahead of Sunday's star-studded concert at Windsor Castle, with hundreds of street parties and Coronation Big Lunches being held across the the UK throughout the day.

The Prince and Princess of Wales were mobbed by the excited well wishers, shaking the hands of many, posing for selfies and having lengthy conversations.

The Prince and Princess of Wales mingled with locals who had gathered for a Big Lunch along the Long Walk outside Windsor Castle as members of the royal family joined community events around the country on the second day of King Charles III's coronation.

The couple were all smiles and seen fully enjoying the moments. They spent time meeting locals, including some wearing crown headpieces. A fan gave William can of beer featuring the King.

Kate and William have shared the images of their first outing since King Charles Coronation to their official Twitter account.

Kate dazzled in a dressed down look as she rocked a light blue blazer over a white top with black trousers and sneakers.

Britons were invited to gather with neighbours for the events, which are intended to "boost community spirit, reduce loneliness and support charities and good causes."

William, 40, and Kate, 41, will join the royals again on the Coronation Concert tonight, where Lionel Richie, Kate Perry will enthrall fans, the Prince of Wales is set to give a speech honoring his father at the event.