Attendees at a Piccadilly street party could hardly believe their eyes when Prince Charles and the Duchess of Cornwall turned up to join in the fun.
A huge cheer went up as the royal visitors appeared, before taking their seats at a tressle table decorated with Union Flags.
Charles and Camilla – who brought along a see-through umbrella – were in high spirits, chatting to guests.
Another cheer went up when a huge union flag cake was brought out to the table.
Afterwards the couple attended a playing of the National Anthem, which was introduced by Green Wing actor Stephen Mangham.
Camilla sang along, and Charles punched the air in jubilation as the rendition ended.
Despite the inclement weather, more than 10,000 street parties were scheduled to take place around the UK.
Several celebrities joined in the celebrations, too.
Actress Barbara Windsor brought a little East End cheer to a west London street party.
She joined more than 100 revellers in Ealing for a Big Jubilee Lunch with a Fifties fancy dress theme.
Kelly Brook hosted a sophisticated soiree with "lots of tea and cake" while Jamie Theakston and Louis Spence were snapped getting into the spirit of the historic day at separate bashes.
- Amanda Holden: "Whole family sooooo excited! We're off to brave the weather to watch The Flotilla!!"
- Emma Bunton: "Such a shame about the weather but I'm determined to have a fabulous Royal day with my boys and family!!!!"
- Joan Collins: "So looking forward to watching the spectacular flotilla today from friends balcony. Can't wait!"
- Henry Holland: "Happy Jubilee Ma'am"
- Ant and Dec: "Morning all, have a great Jubilee day, however you're spending it. D x"
- Alan Carr: "Happy Jubileeing folks!!"
- Davina McCall: "Liz and giant corgi at the beach . Long Live The Queen"
- Patsy Palmer: "So Just looking at the Queen... I’ve met her.. and... i Like her !! have a great day your majesty....God Save The Queen"
- Neil Diamond: "Happy celebrations to my friends in London, wish I could be there with you for the (wonderfully named) #DiamondJubilee!"
- Raymond Blanc: "Is this not a truly magnifique occasion? Full of pomp & circumstance. Lovely to see all the boats #DiamondJubilee #BigJubileeLunch"
- Sarah Ferguson: "Sooo proud of my girls smiling broadly, celebrating Granny with the Nation and Eugie with her flag and both happy smiles"