As I discovered to my dismay during some research at the Public Records Office, many regiments made minor changes in their uniforms on an almost annual basis. The uniform still conformed to the 1768 Warrant, but the regiment outfitted a "Pattern Corporal" reflecting the proposed changes for the next year. Those changes had to be approved before the new uniform could go into production. When it did, the clothing and accoutrements had to look like those of the Pattern Corporal. Unfortunately, the records I looked at didn't give much (if any) information about these yearly alterations.
I'm not sure whether a regiment serving in America went through this process, although it probably did not. Even so, the uniform it wore when it left England was not necessarily identical to the one it wore in 1770, or 1771, or 1772, etc.
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