SwimmerMike: I know zero about this era of Hetchins and less than zero about Charter Lea beyond the existence of the name. But I can suggest that you check out
Hilary Stone's website. He ain't cheap, but he knows his stuff and has all sorts of stuff that never found its way across the pond. I've bought one or two things from him over the years and he is quite reputable. If nothing else, the website is a fun way to lose yourself for several hours.
Nice frame. It is lucky to have found you. I will expect to see it on some future First Saturday ride.