When it comes to science fiction, this topic has been researched extensively over the years, but I find little to nothing about it regarding horror fiction.

My search criteria are:

• It is an anthology (multiple stories by multiple authors), not a collection (multiple stories by one author).
• Contains original material; stories appearing in print for the first time, not reprints.
• Meant for adults, not targeted specifically for children or young people.
• Published in the English language.

My findings are:

• 1971, UK - New Writings in Horror & the Supernatural, edited by David Sutton, paperback published by Sphere.
• 1978, US - Shadows, edited by Charles L. Grant, hardcover published by Doubleday.

Sutton also edited New Writings in Horror & the Supernatural, Volume 2, paperback published by Sphere in 1972, and The Satyr's Head and Other Tales of Terror, paperback published by Corgi in 1975.

That makes three original material horror anthologies published in the UK before the first one published in the US.

Of course, the anthology edited by Grant went on to become a long-running series during the US horror publishing boom of the 1980s/early 1990s along with tons of other anthologies and novels.

Does anyone know of any earlier English language, original material, horror anthologies for adults published in the US or UK?

UPDATE

DavidW's findings are:

• 1962, US - Dark Mind, Dark Heart, edited by August Derleth, hardcover published by Arkham House.
• 1966, UK - Dark Mind, Dark Heart, edited by August Derleth, paperback published by Mayflower-Dell.

Dark Mind, Dark Heart is notable for including the first Cthulhu Mythos story by Ramsey Campbell.

The Arkham House hardcover had a print run of 2493 copies. I'm assuming the Mayflower-Dell paperback was probably a mass-market paperback with a much larger print run.