The Nancy Drew Mysteries
Biggles
Billy Bunter at Greyfriars school
The pony novels of the Pullein Thompson sisters
The Famous Five and the Secret Seven and the Mallory Towers books
Angela Brazil school stories
Goosebumps
And so on. There are yards more. They are the books generations of children read by torchlight under the bedclothes, in the years BP ( you can work it out.) They are the books we could not get enough of, which our parents and teachers thoroughly disapproved of, which were confiscated - they replaced them with Children's Classics like Heidi. But we read on in secretly and the joy and absorption and fun those books gave us led us to become readers, to seek the magical experience of opening a new book and falling head first into it, the books that set us off on the road.
I love to see a child curled up immersed in a book in that way. Whatever the book, if it leads to the love that lasts a lifetime, it gets my vote. It is a Great Book. It is Influential.