What is one of your favorite childrens stories?

Over the years my favorites changed. When I was 7 to 10 years old my favorites were two series by a children's author called Enid Blyton. One series was called the Secret Seven and the other was called the Famous Five. Both involved the adventures of a group of kids who solved mysteries or who had adventures.

Then as I got into my very early teens I enjoyed the stories of Captain W.E.Johns whose stories featured a fellow called Biggles who was a pilot in the Royal Air Force. Another Series had Gimlet as a hero. Gimlet was known as the King of the Commandos, and then yet another had Worrals a girl who was a pilot in in the Women's Auxiliary Air Force. However the story that made the biggest impression was a book about a group of children who went to stay with an uncle on their holidays and he had arranged an adventure in self sufficiency for them.

He put them on to an island in the centre of a river with a few possessions just as if they were shipwrecked. They then had to become self sufficient using what they could find. Uncle had seeded the island's beaches with "wreckage" from the ship but they had to learn to adapt things for other uses, make shelters, learn to fish and trap and so on. Unfortunately I have no memory of the title or the author.