How do the good gambling people in the United States manage?
Sports betting, Poker, Horse Race and Casino winnings are all taxable income. You even get your picture taken on the horse track if you win over a certain amount (I think it's $5k), near the pay out window!
https://www.efile.com/taxable-gambling- ... ome-taxes/
Wouldn't take much of a tweak for the UK to fall in line at some time.
Theoretically, you could report your winnings year on year anyway. Use an accountant that knows how to fudge/present your figures, along with any other income over the tax year. That way you're covered and it's up to the HMRC to decide. (we already know their decision).