A Squirrel Called Cyril — Rosemary J. Peel

Gemma has got herself into a pickle; she told a lie in front of the whole class and can't withdraw it. As lies do, it snowballs. She is desperate and doesn't know what to do. She wishes she'd never told the untruth and promises herself never to do so again. Then a miracle happens; she spies a squirrel's tail hanging down through the ivy on her garden wall - all may not yet be lost.