Seance on a Wet Afternoon by Mark McShane (1961): And She Ain't What You'd Call a Lady

A slim but successful suspense thriller, Seance on a Wet Afternoon isn't really a horror novel, but I read it solely for that wonderfully evocative, moody title alone (I've long known about the movie adaptation but have never seen it). Mark McShane (1929-2013) was an Australian author of crime fiction, which is what this novel basically is. The "supernatural" aspect is a psychic woman, or a "sensitive," Myra Savage, who makes extra money by holding seances with neighborhood ladies. Myra concocts a plan of utmost practicality: kidnap a well-to-do child for ransom, but then she will reveal through her powers the child's whereabouts, find the money, and then go from rags to riches thanks to the resulting fame such a good deed will engender. 

Back cover of above, cover art by the great Harry Bennett, Jan 1965

Except of course that's not how things go, they never do, thanks to her husband Bill (poor sod). Together these two make quite the toxic couple. The results are top-notch suspense and a true banger of an ending. McShane really knows the landscape of London and surrounding working-class towns, which I always appreciate reading. His depiction of morally compromised characters who justify their selfish, deluded actions is razor-sharp. 

1963 Pan Books, UK

Again, not really horror, but very tense and unsettling in places; while the downbeat "rainy afternoon" vibe will appeal to fans of Ramsey Campbell or Robert Aickman, I think, fellow British writers with a delicate, knowing pen and a penchant for ironic twists of fate.

He took one step back from the peephole. He closed his eyes tightly. He was overpowered by a feeling of horror; black dripping horror. His lips, mouth, his whole lower jaw began to tremble. The moan that escaped him tuned up to a squeak at the end. As though he'd been stung on it, he pulled his hand from the girl's face...