In the novel "Brighton Rock", Graham Greene refers to a "half-crown enclosure" in the context of horse racing.
My guess is that it may refer to a type of horse race where half-crown refers to a betting limit, or the size of the purse or payout.
Alternatively, the phrase may refer to a type of race track.
I tried searching the internet but found no explanation except for a few vintage postcards.
Any insights would be appreciated.