a blot on your escutcheon
a blot on (one's) escutcheon
A stain or mark against one's reputation or that of one's family. An escutcheon was a heraldic shield that bore a family's coat of arms, and thus serves as a metaphor for one's honor. I was at the top of my class in college, but that narcotics charge will be a blot on my escutcheon for years to come.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
a blot on your escutcheonor
a blot on the escutcheonBRITISH, OLD-FASHIONED
If there is a blot on your escutcheon, you have damaged your reputation by doing something wrong. For the leaders, this is probably a blip rather than a blot on the escutcheon. Note: An escutcheon is a shield, especially a heraldic shield displaying a coat of arms.
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012