I read this book, which I think was a collection of short stories, at school in the UK in the late 1980s/early 1990s. One story has stuck with me as I found the ending quite spooky at the time.
The story involves a young boy who I think is being bullied by some other boys. The ending of the story involves a wall and, for reasons I can't remember, the bullied boy challenges one of the bullies to run directly into the wall.
The bully somehow passes through the wall and finds himself in a grey and featureless place (I don't think it explained what or where this place was) with no way back. He rants about getting his revenge on the bullied boy when he gets back and the story ends with a line something like "But of course he never did."
Unfortunately I can't remember the author or any other details.