Trilby, we were allowed free choice and some favoured pork pie hats, I think mine was Tyrolean with a feather. They were quite popular too. A flat hat was also either permitted or required. I had a Kangol which survived well into the 80s and saw much service when gardening. It was eventually replaced in the 90s with a Napoli, that I saw in Naples but was still made in England.
Now I rarely venture outdoors without a Fedora, Panama, or one of several tweed caps all worn for their thermal and waterproof qualities rather than as a fashion statement.