Well spotted an interesting capture Hazel , I was never into Enid Blyton as a child and will not be buying myself an adult one any time soon, bah humbug:)
Yes, this is a strange title! They really seem to have gone to town on this series! (I gave my daughter '5 go to Brexit Island' for Christmas, as she was so infuriated by the vote!)
The sign is quite funny too, "sheds" and "more sheds".
Yes, I guess the publishers are quite clever - I had similar thoughts to you!
I loved Enid Blyton
I think dads disappear on purpose :)