Kate's fears for Pippa's wedding

Kate Middleton has revealed her nerves for sister Pippa and that she fears George and Charlotte will misbehave at the highly anticipated wedding ceremony.

The Duchess of Cambridge is worried her two children will take centre stage with their antics when Pippa marries James Matthews this Sunday.

The princess let slip her fears, to a family employee, that the youngsters might not be on their best behaviour for the special day.

The Sun claims Kate confided in Andrew Bates, who previously worked with the Queen, at a recent Buckingham Palace garden party.

Bates told The Sun: "She said that they were all really looking forward to her sister's wedding at the weekend but she was a bit worried about how her children might behave.

"She said she was hopeful that they would be good but you never know at that age."

Will the cheeky pair steal the show? Photo/Getty

Three-year-old Prince George and two-year-old Princess Charlotte will be key figures in the ceremony, acting as page boy and flower girl.

The highly anticipated wedding will take place this Saturday in Berkshire and is set to be the society wedding of the year.

This story originally appeared in the NZ Herald and has been republished here with permission.