As far as I can tell, she does bugger all. All down to our civil wars and Oliver "Ironsides" Cromwell.

Here's a nice fact for you: At the start of his reign King Charles I (Of England) was 5' 4" tall. At the end of his reign he was 4' 8" tall.

Because of the old Royalty being better than God argument, Parliament now runs the country and the Queen does nothing more than...erm...Queen.