There's just been a thread on LibraryThing's "Name that Book" forum: ghost story -- England -- couple changed by house. The work sought sounded remarkably like PG Wodehouse's Unpleasantness at Bludleigh Court - which features a young artistic couple who become hunting-obsessed due to the malign influence of a country mansion belonging to one of their relatives. Collective effort, however, tracked it to John Buchan's story Fullcircle: Martin Peckwether's Story.
This concerns an earnest young intellectual couple ...
"Julian and Ursula Giffen. . . . I daresay you know the names. They always hunt in couples, and write books about sociology and advanced ethics and psychics--books called either 'The New This or That,' or 'Towards Something or Other.' You know the sort of thing.
... who move into a small Restoration manor house inherited from one of their relatives, and become benignly altered by it until their attitudes are in tune with those of its amiable Catholic originator, Lord Carteron.
It's the final story of Buchan's The Runagates Club, his 1928 anthology of stories connected by the framing device of storytelling by dining club members (who include Richard Hannay and other Buchan heroes). Given the date and strong similarity in premise and plot, I think it's very likely that the 1929 Unpleasantness at Bludleigh Court is a pastiche of Fullcircle.
Wodehouse was, after all, a skilled parodist. This isn't generally remembered because - compare Stella Gibbons and Cold Comfort Farm - the objects of his parody have gone into obscurity. Jaime J. Weinman sums it up well:
Almost everything he wrote began life as a parody of some then-popular genre of stories. Stories about idle young men who belong to clubs (the Drones Club stories, the Bertie and Jeeves stories), "frame" stories told by old adventurers (Mr. Mulliner; the golf stories), stories about stern Aunts who won't consent to their niece's marriage (the Blandings series); these were all familiar to readers when Wodehouse started doing funny versions of them ... At the time Wodehouse started writing for the Saturday Evening Post, these were types of stories that were being told seriously in the Post and many other magazines, and Wodehouse basically made his name by writing stories that took those elements and rechannelled them into farce.
- Wodehouse the parodist, Something Old, Nothing New: Thoughts on Popular Culture and Unpopular Culture, Jaime J. Weinman
Jaime goes on to mention, for instance, the connection with Ethel M Dell, who appears in Wodehouse works as Rosie M Banks.
Addendum. More complex, it seems. In a follow-up - Reciprocal Wodehouse Linkage - Jaime points out that the 'malign house' theme is widespread, and also appears in Wodehouse's earlier Honeysuckle Cottage (1925) in which a writer of hardboiled crime novels, James Rodman, moves into the cottage of a late aunt who was a successful romantic novelist, and finds himself increasingly under the malign influence of sentimental fiction.
Judging by The Figure in the Carpet of "Honeysuckle Cottage": P. G. Wodehouse and Henry James, Wernsman, Marijane R. Davis, The Henry James Review, Volume 26, Number 1, Winter 2005, pp. 99-104), Honeysuckle Cottage draws strongly on Henry James and The Turn of the Screw, which it even mentions:
"Do you believe in haunted houses? Do you believe that it is possible for a malign influence to envelop a place and work a spell on all who come within its radius?" ...
"Of course, ... one has read stories. Henry James's Turn of the Screw ...
Then again, I just found that Buchan's Fullcircle first appeared in magazine form in 1920, putting it among the many possible precursors to Honeysuckle Cottage too.