I've never read any kind of spy/espionage novel, not a LeCarre or Ludlum or Fleming in all my entire collection of paperback fiction, so admittedly I'm intrigued by ones that have a supernatural twist to them, especially when it seems to have been done with skill and invention (Clive Barker did such a thing in his short "Twilight at the Towers"). The word "ingenious" gets mentioned with Blackburn a lot, and man, I just don't read enough books that make me go, "Wow, now that was ingenious!"
Anyway, I'm posting these old paperback covers solely because I dig 'em; don't you? I mean that Children of the Night (Berkley Medallion/1970)--one of the most over-used titles in all of horror, thanks Count Dracula!--is something to behold, a true creepfest, as nudists there seem to be enjoying an adults-only getaway in a monster maw.
The title-switch of New-Mown Hay to Reluctant Spy (Lancer/1966) makes sense; I'm the sure the original title refers to some moment of dreadful import within the story itself (although I don't think it refers to a bikini-clad ass [NEL/1976]), but for unfamiliar readers it doesn't exactly scream "must-buy!". The stark simplicity of cold marble and black iron of Bury Him Darkly (Berkley Medallion/1970) bespeak... well, someone buried darkly.
For Fear of Little Men (Coronet UK/1974) uses poor John Merrick to some touching effect, and the juxtaposition of rat and child on Wreath of Roses (Lancer/1966), might that be a precursor to a Mr. James Herbert? Perhaps. Broken Boy (Lancer/1966) has a good review and some author background here. "Cold-war espionage" leaves me, well, cold, but knowing what I know about Blackburn now, I wonder. Cold war? I think it likely also means cold chills....