From Chelsea Pensioners official website :
2. BUTTONS
Originally made from brass, each coat has nine buttons. In 1959 the brass buttons were replaced by anodised ones,
which was incredibly popular with the Pensioners as the new buttons didn’t require polishing. The buttons are engraved with the symbol of the crown and the letters RCI, the initials of the Royal Corps of Invalids (to which the Chelsea Pensioners were once a part of).
https://www.chelsea-pensioners.co.uk/scarlets
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