Successful children's writers generally get a couple of decades in the sun. My own favourite as a child, Malcolm Saville, published his first Book in 1943 and got a little longer, but in his last years (he died in 1982) he was painfully aware that he had gone out of fashion. 

Enid Blyton's reputation has not declined to that extent, but there has been a price to pay. Because, for decades, her books have been edited and re-edited so that they can still be sold. So much so that these days you have no idea how many of the words in a book with her name on the cover she actually wrote.

I don't like this process: I would rather publishers allowed books go out of print gracefully than mucked them about in this fashion. But it is inevitable, because publishers and writers' estates aren't going to slaughter a cash cow.