Strangely, a character named Judas figures in the play. One of Bonduca's daughters refers to him as -
That hungry fellow, with the red beardNo doubt tapping into the common notion that Judas sported red hair. True to form Judas is also devious, cowardly and self-interested in the play.
I'll take this as more evidence of a general belief that red hair was a token of distrust.
As for the play itself, it was fairly entertaining. It was loosely based on the story of Boudica as told by the writers Cassius Dio and Tacitus.
Interestingly, Cassius Dio described Boudica as having long red hair that hung below her waist. He also stated that she wore a many-coloured tunic and a large golden necklace.