Our two cats are 6 months old and we haven't let them out yet. But last night someone broke in (we are away) and neighbour who is feeding them says one of the 2 cats is now missing - presumably escaped through the open window.
They are chipped but obviously haven't been out before, it's very cold and there is no way for her to get back in, unless neighbour stays at ours to keep an eye out, which they obviously can't do all day.
Come and cheer me up with tales of returned cats as I'm miles away, dealing with 3 distressed DC while trying not to panic myself.