Here Comes Thursday - Michael Bond, HarperCollins Publishers

The tale of a lost mouse who finds a new home Thursday the Mouse fell from a balloon having just escaped from the Home for Waif-Mice and Stray-Mice. The Peck family of church mice adopt him and give him his name – Thursday – because the day he arrived was a Thursday to remember. Thursday joins the Pecks in their organ-loft home at the church of St Mary's in the Valley.