Taxonomic Puzzle

Making the tea looked out of the window to see the mouse is back. A few days ago I blipped him as a small rat. I've seem him a few times since (once there were two of the beasties) and decided he's a mouse that looks bigger when he stretches. But after pointing him out to Alison I can tell she's not convinced. Next door's cat seems to be on holiday but when he returns I don't expect he'll worry too much about the niceties of classification.