Thursday's child has far to go--not so Thursday the mouse, an escapee from the Home for Waif-Mice and Stray-Mice who joins the Cupboardosities in a series of musty mice-takes. He thinks a collar stud is a pearl and a bird being ""tortured"" in a wooden box turns out to be a cuckoo clock. In changing the family store to a self-service supermarket, Thursday unwittingly writes ""Help Yourself"" on the sign, and the resulting chaos depletes their inventory and the family fortunes. Too bad--and the German scientist and American cousin stereotypes are equally cheesy. The distinctive style and offhand humor which give the Paddington books their pizazz are disappointingly missing, and Thursday is just another weak-day.