E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
Collar-day (A).
In royal levees, means that attendants are to wear all their insignia and decorations, such as medals, stars, ribbons, and orders. This is done on grand occasions by order of the Crown. The Queen’s Collar-day is when she wears the Order of the Garter.
a,
