London, England -- Prince William will ride through central London on horseback as part of his grandmother Queen Elizabeth II's official birthday celebration.
The newly-wed prince will take part in Saturday's "Trooping the Colour", a procession held every year to mark the monarch's birthday.
The queen turned 85 in April, but the public party for the monarch's birthday is held on a Saturday in June when the weather is better. The custom dates from 1748 and will be June 11 this year.
William is expected to wear the same red Irish Guards tunic with a bleu sash that he wore at his April 29 wedding to Kate Middleton at Westminster Abbey.