What is the proper headwear in the for this?

[Edward]

It has stylistic echoes of the much shorter mess dress jackets worn by British military. I'd be thinking 50s band uniform type of thing. Could be a good option to use for a smoking jacket.

 

[GWD]

Interesting jacket, I must say! I wonder if that was formerly a uniform of sorts; or perhaps a jacket intended for some religious or fraternal organization. Do you know when it was cut?

No idea, it's a Pendleton I'm guessing 50's or 60's, it's the only one like it I've seen. I doubt that Pendleton produced uniforms, although I have nothing to back that statement up. My guess is that is was marketed as a holiday jacket or maybe even a smoking jacket. [huh]