I had a quick look through some Dawes catalogues on the V-CC library site.
Those steeper inclined dropouts may be a little earlier than you are guessing.
Unfortunately they are only illustrations and not photos in the images I've looked at but lug patterns/shapes are visible.
As
@juvela says above, images of the lugwork may be helpful.
if you can get a good photo of the seat cluster area from the same angle as your previous photos above, and also the head tube area, I'll see if I can help.