He had shown very little interest in going out - been out a couple of times with me in the garden and pretty much gone straight in. Also gone out alone maybe twice unnoticed but been back within 20 mins or so and I don't think left the garden. I have another cat and hadn't realised today that new cat had access to garden and he had probably been gone around 45 mins before I noticed. Now been gone probably 90 minutes. Been calling and calling and nothing. Definitely not in the garden. I've walked around the streets but nothing. The back garden has fences and only really has access to other back gardens on other streets so had to walk near where he must be. I'm so worried.