Born in County Durham, he joined the British Army's Royal Military Police and wrote stories in his spare time before retiring with the rank of Warrant Officer Class 1 in 1980[1] and becoming a professional writer.

In the 1970s he added to H. P. Lovecraft's Cthulhu Mythos cycle of stories, including several tales and a novel featuring the character Titus Crow.

Other stories pastiched Lovecraft's Dream Cycle but featured Lumley's original characters David Hero and Eldin the Wanderer.

The central protagonist of the earlier Necroscope novels appears in the anthology Harry Keogh and Other Weird Heroes.

[6][7] Lumley's list of his favourite horror stories – "not complete by any means and by no means in order of preference" – included M. R. James' "Count Magnus", Robert E. Howard's "The Black Stone", Robert W. Chambers' "The Yellow Sign" from The King in Yellow, William Hope Hodgson's "The Voice in the Night", and H. P. Lovecraft's "The Haunter of the Dark" and "The Colour Out of Space".