Millicent and Meer will be a popular book choice.
One day when Millicent is busy building sandcastles a big wooden box lands beside her. Inside there is a little animal. Millicent sees the word kat - problem solved the animal is a cat and she also sees the word Meer - another problem solved his name is Meer.
Millicent takes Meer home but is behaviour is very "uncatty" and her family begin to despair. Then Meer meets a real cat and together they solve the mystery of his identity and in the process find the meerkats at the zoo. The ending is very satisfactory for all involved.
This is not major picture book but the illustrations are very special. I was not at all familiar with Richard Byrne but I will now seek out some other books by this talented UK author/illustrator.