I for one wouldn't think 1970s, even though I lived through that decade. The shirt, usually a sport shirt, worn over the jacket or coat collar, goes along with wide trousers, short back and sides haircut and so on, maybe even with brown and white shoes, not that I ever remember seeing anyone dressed like that. All the adult men I ever knew or saw in the 1950s were either dressed up, as for Sunday, or wearing work clothes. None of them, save one, ever wore what would be called casual clothes. The one exception was a man who liked Orlon polo shirts.
Does anyone remember those transparent pastel-colored nylon shirts that boys might have worn in the 1950s?
Does anyone remember those transparent pastel-colored nylon shirts that boys might have worn in the 1950s?