Children's author Julia Donaldson has revealed the new title and lead character of her much-anticipated new Gruffalo book.

Gruffalo Granny - the third in the popular series about the fictional monster and his family and friends - will be released in hardback and audio book on 10 September.

Twenty years in the making, it will see the introduction of the new family member, while old favourites from the first two books will also return for "an exciting new adventure", publisher Macmillan said.

The announcement was made on BBC Radio 4's Today programme on Friday. Donaldson - who creates the stories alongside illustrator Axel Scheffler - said: "It's always a challenge to write a sequel".

A picture of the new character will be released later on Friday.