The evidence was that the 'uniforms' had been made by local tailors. Coster, who admitted having one made, said it was a 'uniform de fantaisie', largely to protect him from questioning. The tailor who made four green coats at Aumale said they were 'en bourgeois', in neither case did the prosecution produce contrary evidence.
How many other 'uniforms' there were or what they consisted of is vague, I suspect they were largely, as Coster said, used because men in uniform got respect. One of the conspirators had earlier worn uniform to persuade a credulous Norman farmer that he was on government service and that the men who would need lodgings were on a secret government mission, so this did work.
regards,
Susan