I have seen Peaky Blinders. It was pretty good in the earlier days but lost its way towards the end. I have no desire to see the recently released film.
One of the earlier episodes was set at the Derby but I don’t know if the Peaky Blinders inspired flat cap at the races trend was already in full swing or if that started it off.
Never worn one myself, I prefer the practical warmth of the beanie although admittedly it is far from stylish.