This is my first 'vintage' shirt but I don't know what vintage. I can't seem to decide whether it is 1930s-1940s or 1970s, though I'm leaning towards the former. It has high armhole, a long pointed collar, french cuffs, a 'pleated' back (see pics) and an interesting fabric pattern. It is in nearly perfect shape and was hanging in a rack of 1970s clothing, which makes me wonder. Edit: it is an "Ambassador" brand shirt and was woven in England. Can any of our shirt experts help? Thanks.