Over the last couple of weeks he has disapeared for a couple of nights on the trot, which isn't unusual, but last week he went off for a couple of nights then came back with no collar and smelling of someone else's perfume! We've always suspected he goes off to other people's houses for food and such (he's a greedy fat cat) and I put the missing collar down to it being fairly old and worn...maybe it had stretched and he'd managed to get it off somehow.
So on Thursday I bought him a plasticy collar and one of those ID tubes with a bit of paper inside with his name and our contact details on it. He came home this morning after being out from Saturday night, and collar is missing again

I'm not too bothered about him going in people's houses, he knows where his home and I don't think he would ever go away for good, but I'm worried about him walking around without a collar on in case he is mistaken for a stray and taken somewhere.
Is there anything I can do to stop this happening bar keeping him in the house all day?