Recently I've a read a couple of Ryan's many short stories, published throughout the 1980s in various anthologies like Shadows and Whispers. As an editor he compiled Halloween Horrors (1986), a fave of my teenage years The Penguin Book of Vampire Stories (1987), chilling stories by famous female writers in Haunting Women (1988), as well as the first in the long-running horror anthology series Night Visions, In the Blood (1984).
"... horror fiction offers some pretty extreme critical situations, extreme in the sense of being even more than life-threatening. It offers a set of conventions that allow a character to be challenged in a way that threatens perhaps everything he believes in - very basic things, including his grip on reality. I'm interested in seeing what characters will do when confronted by some ultimate evil - not something as trivial as losing a job or a girlfriend, the sorts of things that so much mainstream fiction is about - but really dark, unfathomable evil, evil that is cruel and random in the way it frightens and inflicts pain."
From Ryan's interview in Faces of Fear (1985).