Er, no idea about the others, but Blyton used to be a popular author of childrens books. My friends and I read German translations of the Adventure series or the Famous Five series. If I remember correctly, a lot of her books took place in boarding schools, which was a bit excotic for us. I always took her as classic childrens lit and wiki says she was translated into alomost 90 languages. definitely not a local phenomenon. ;o)
http://en.wikipedia.org/wiki/Enid_blyton