hello norman from across the pond, both Ken and Stephen gave you very good responses, I would only like to add one other possibility. At one time there were many who believed that many of the orginal confederate jackets were grey, and had over the years due to the sun bleaching out the grey color mixed with body sweat, altered many confederate uniforms to a dingy butternut color. I believe this has taken place and have a jacket that I first used in reenacting which was a confederate grey material and would never be mistaken for butternut, but now has changed over the years. I have a friends shell jacket purchased at the very same time but with much less use and he always had it dry cleaned after each event, and it still looks the orginal color, mine however has shifted to a more dirty or dingy color and could be confused with that of butternut. My jacket on the other hand was never dry cleaned, but simply left outside to dry in the open air.
This doesn't not mean that I think Butternut wasn't used, just another example of where some of the orginal jackets color may have come from.

The only orginal example of the company jacket we use, company K 3d La. infantry looks brown and is. But when you look at the thread colors closely you find that there is a mixture of wool-jean material, and many of the threads making the jacket are yellow.

curtis