If you find an item of value and do not attempt to find the owner you can be done on the of fence of ‘stealing by finding’
Would this apply to a winning lottery ticket?
Firstly I have not found one unfortunately 
, but I heard on the radio yesterday about an unclaimed Euro lottery ticket, and 5 minutes later I found one on a forecourt, and thought it was some kind of fate thing going on 
It looked like it had dropped out of a wallet rather than being chucked, as a coffee loyalty card was wrapped in it and a receipt from a cafe. Anyway I checked it and it was a loser, but what if it had been a 10 mill winner, how would I stand by law?
BTW only two more Maccy D’s lattes to buy for my freebie.