The Guards, being older than most, are more idiosyncratic than most. An American major, serving temporarily with the Blues and Royals in Detmold in West Germany, was amazed at the number of times the officers appeared to change their uniforms throughout the day. "Officers sometimes spend hours discussing what they are going to wear next day," a Grenadier confirmed in Berlin.
What Guards officers wore off duty used to be considered almost as important as what they wore on the barrack square. Pinstriped, conservatively cut suits, bowler hats, and rolled umbrellas--never to be unfurled, come rain or shine--used to be obligatory. But now the rules are more relaxed, as they are with other things, such as officers beling allowed to use London's public transport system and to carry parcels under their arms.
The officers of the Queen's Guard at St. James's Palace can swim or play squash at one of the Pall Mall clubs around the corner during their tour of duty. But in spite of more relaxed rules they must still walk there in full ceremonial uniform. And military decorum still insists that an officer thus attired may not carry anything else. So, at a discreet distance behind him, the officer's orderly will follow, bearing squash racket, shoes, shorts, jockstrap, swimming trunks, and anything else the officer may need.
The Guards, John de St. Jorre and Anthony Edgeworth (1981)