Every Dog — William Mayne

The field next door has been sold, and Robert watches as work begins on the new primary school to be built there. But by night and by day different plans seem to be taking shape, and no-one knows just who is in charge. Oggin, the ginger cat, would like to be, but sometimes a mysterious dog appears to confuse things - or does he? Objects from the old school bring back memories which Robert's Dad can't quite explain, though Mum is able to guess some of the answers. Someone or something is determined that the new school will not forget the old school. Meanwhile, the new headmaster and his tiresome daughter are ready to move in as soon as the school is finished. The oddness doesn't stop till the opening night, but there is an explanation in the end, if you believe that sort of thing. Oggin doesn't, but he tries his best.