Red

(Heraldry) See gules.

To colour fabric, several dense red dyes were used in period, including madder, and brazilwood.

In England, in the latter years of period, scarlet red became the Royal livery colour, reserved to the Crown and its direct servants. Which is why judges wear it, and why (until they are banned) fox-hunters do so, as the hunt is technically a Royal prerogative, and they are deemed only to hunt under Royal let.