As described here, the story concerns a budding romance between two gentle poets, Aubrey Trefusis and Charlotte Mulliner, that is interrupted by the malign effects of a country house - Bludleigh Court, Lesser Bludleigh, near Goresby-on-the-Ouse, Bedfordshire - that afflicts everyone who stays in it with a lust for hunting. Charlotte thinks she has been unaffected until she finds herself aggrieved that one of her poems has been rejected by The Animal-Lovers' Gazette
(A Vignette in Verse)
When cares attack and life seems black,
How sweet it is to pot a yak,
Or puncture hares and grizzly bears,
And others I could mention;
But in my Animals "Who's Who"
No name stands higher than the Gnu;
And each new gnu that comes in view
Receives my prompt attention.
When Afric's sun is sinking low,
And shadows wander to and fro,
And everywhere there's in the air
A hush that's deep and solemn;
Then is the time good men and true
With View Halloo pursue the gnu;
(The safest spot to put your shot
is through the spinal column).
To take the creature by surprise
We must adopt some rude disguise,
Although deceit is never sweet,
And falsehoods don't attract us;
So, as with gun in hand you wait,
Remember to impersonate
A tuft of grass, a mountain-pass,
A kopje or a cactus.
A brief suspense, and then at last
The waiting's o'er, the vigil past;
A careful aim. A spurt of flame.
It's done. You've pulled the trigger,
And one more gnu, so fair and frail,
Has handed in its dinner-pail;
(The females all are rather small,
The males are somewhat bigger)
Unpleasantness at Bludleigh Court first appeared in the Strand Magazine, Volume LXXVIII, January-June, 1929. It can be read online in A Wodehouse Bestiary. Although it's comic in tone, its premise is quite Lovecraftian, and the story was reprinted in The Magazine of fantasy & science fiction in 1952.
Addendum, 21 Sept 2009. 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 Unpleasantness at Bludleigh Court, but collective effort tracked it to John Buchan's story Fullcircle: Martin Peckwether's Story. It 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 Restoration mansion and become altered by the house until their attitudes become 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.