Hi Heather, That's really kind of you, thank you for getting in touch :) We kept him in for 4 days, which I know isn't long enough and in retrospect we should have held out against his will, but he was going pretty potty and destroying the house and furniture being kept inside! He did go out and come back a few days and nights, so we were quite comfortable-ish he knew how to get back. The house has a catflap into the back garden, but there are parts from the neighbours' gardens where he could potentially have got out onto the street. Fingers crossed that he's ok, hopefully he shows up sooner or later. Thanks again!