E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Bow Street runners, who wore a scarlet waistcoat.
The Bow Street runners ceased out of the land soon after the introduction of the new police. I remember them very well as standing about the door of the office in Bow Street. They had no other uniform than a blue dress-coat, brass buttons and a bright red cloth waistcoat The slang name for them was Red-breasts.Dickens: Letters, vol. ii. p. 178.