There are three daily parades in London: the Ceremony of the Keys, Dismounting Ceremony, and Changing the Guard at Horse Guards. The parade at Buckingham Palace is sometimes every other day. Annual parades include the State Opening of Parliament, Trooping the Colour and Remembrance Sunday.
Craig recommends… The Ceremony of the Keys is my personal favourite, but Changing the Guard is so popular that I had to put it at No.1 in my London Bucket List. I quite like the Dismounting Ceremony as well.