(A). A boatman's jacket. Properly and originally applied to the Johnian crew (Camb.), whose boat jackets are the brightest possible scarlet.
“A blazer is the red flannel boating jacket worn by the Lady Margaret, St. John's College, Cambridge, Boat Club.” —Daily News, August 22nd, 1889.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
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