Sophie Kinsella 
Mummy Fairy and Me: Mermaid Magic 

The fourth book in this magical series for 5-7 year olds, from global bestselling author Sophie Kinsella.
My mummy looks normal, like any other mummy . . . but she »s not. Because she can turn into a fairy. All she has to do is stamp her feet three times, clap her hands, wiggle her bottom and say  »Marshmallow » . . . and POOF! She »s Mummy Fairy.
Ella »s family has a BIG secret – her mummy is a fairy! But sometimes Mummy Fairy »s magic goes wrong, and then it »s up to Ella to help. In this fourth enchanting book, Mummy Fairy and Ella decorate the kitchen with magic colouring pencils, catch a robber on Ella »s school trip – and swim with real mermaids!