a red jacket worn by Cambridge's Lady Margaret Boat Club as a'red Guernsey or blazer

It was a bright 🛡 (or blazing) red colour, which is how it got its name  the blazer.

e History Of The Humble Blazer 🛡 - Collier & Robinson colli

you're even wearing a white

ess shirt. We like to compromise by saying the sleeve should land 🛡 just above the wrist