I first came into flat caps when coming up with a uniform for a morris dancing side I had recently helped form. The person who suggested it was a big peaky blinders fan and I imagine that swayed his judgement. I’d never worn one before, but once I’d got one I found that I quite liked it and crucially so did my (now) wife. I have a ridiculously big head (with lots of hollow space) so for a hat to suit me and for my wife to agree was a bit of a miracle.
My dad bought me another one a couple months later as “an alternative by way of change”… I don’t think he was keen on my original choice.
I’ve worn it to the races ever since.