The Changing of the Guard at Buckingham Palace is a bit of military flummery that nominally provides security for the monarch but in reality keeps the tourist dollars flowing.  The sight of humans imitating automatons in ridiculous hats attracts the gawping attention of those in need of regular trivial mental stimulation. At 6 pm every evening a similar change-over occurs in police stations around the country.  This attracts no attention at all and the mechanics of it are unknown to the general public.  But perhaps they should be.