In 1965 I was walking along Whitehall in civvies (no hat). In front of me was a man with hat (on head). From a building emerged a Guards warrant officer in 'full fig' with pace stick who came between us. We three, in our little column were approaching the cenotaph, when I heard this bellow from ahead: "Your hat Sir". Said man in front quickly whipped off his hat and the Guards WO, threw up the most immaculate salute I had seen. We carried on before breaking off to our own business - never forgotten it though.
Old Duffer