Thanks for sharing, Dave - it's a beautiful tie, especially when you consider when it was tied.
I was only able to find two references to the 'Carson' and both recipes had a hackled collar of brown and no yellow roof or underwing. Is your post a variant - and do you have the original pattern recipe?
Also, would you happen to know where I can find more information on Jim Pray and his flies?
On another thread Dave mentions Bates' "Streamer Fly Tying and Fishing", which is also a good source of information on Jim Pray and his patterns. I'd suggest either the 1950 or 1966 editions as they are more contemporary with Pray. Bates' "Streamer & Bucktails The Big Fish Fies," also has a fair amount of material on Pray and his flies, but this was published in 1979 as an update to the earlier book and some of the older material may have been abridged.