The Duchess of Cambridge's party-planner sister Pippa has joined forces with Prince Harry to ensure Kate's 30th is a night to remember.
The pair have apparently planned an Eighties-themed birthday bash complete with cocktails and karaoke.
According to Grazia magazine, who cite a "royal source" as their mole, Harry and Pippa have planning the party for months.
Save the date cards have been sent out to guests, with the information that the gathering will probably take place in London.
Prince William and Kate are expected to attend the premiere of Steven Spielberg's film War Horse in London on the eve of Kate's January 9 birthday.
The royal couple will make an appearance at a £10,000 a ticket charity dinner afterwards, but then they are free to party.
More on William and Kate
Photo: © Getty Images