One was accepted, and set him on a career path that has undoubtedly helped engender a love of books in thousands of children. His famous line drawings dot the pages of books by Roald Dahl and Michael Rosen among others.
Blake's biggest mark has been made on a building by the exit of St Pancras station in London, where Eurostar travellers are greeted by a 16-metre-high historic building wrapped in a Blake mural.
But along the way, he also gained a postgraduate teaching diploma from the Institute of Education, and ever since he has worked to support teachers, just as his Latin teacher encouraged him.
This week, Blake, 75, returned to the institute to collect an honorary doctorate in literature, which accompanies the CBE awarded to him by the Queen, and the Officier de l'Ordre des Arts et des Lettres from the French government.
So how is it that a man who has never had children can develop such a rapport with young readers?
"I tend to approach the subject of children's books as a teacher rather than a parent," he said last year. "In other words, I try to identify with the children in the books, rather than look upon them as a benevolent adult."