Some video clips from the processions before and after The Colonel's Review of Trooping the Colour on 4th June 2011:
This is the first rehearsal of Trooping the Colour on which the Duke of Cambridge (Prince William) has ridden.
An article in The Daily Mail shows photos of Prince William dressed in a red guardsman's uniform, taking part in the rehearsal of Trooping the Colour:
Just another soldier or the heir to the throne? Busby-wearing Prince William blends in during horseback drill
That poor dog - the Irish wolfhound mascot - didn't look at all happy taking part in the parade!