Catch me if you can!

So this cat had been ‘visiting’ us for months now. Always hungry. At first he kept coming through our cat flap which caused chaos as our Mittens really didn’t like him and the others are scared of him. So I eventually kept a bowl of food for him outside and that stopped him coming in. I even bought a wee cat shelter for him in case he’d nowhere to go on the freezing nights - but I don’t think he’s ever used it.
Then a few days ago he turned up with multiple bites on his face. I knew there was no way I could catch him and take him to our vets. I posted on local Facebook groups that dealt with missing and found pets. A few people thought they knew him but no one claimed ownership. Eventually I contacted the SSPCA who have now given me a cat trap to try and get him. If successful they will take him away, get his wounds treated and hopefully find his owner or find him a new one. I only hope I’m doing the right thing.