The Shooting Party by Isabel Colegate.
It's the autumn of 1913, and a party of guests has gathered at the country estate of Sir Randolph Nettleby. In addition to the usual lavish banqueting and quaffing of burgundy and port, there is also to be a game shoot; the regular hosting of these on his estate is a source of some pride to Sir Randolph, and to his team of gamekeepers and beaters.
We meet the guests: Lord and Lady Hartlip, Bob and Olivia Lilburn, Count Tibor Rakassyi, Sir Reuben Hergesheimer, Charles Farquhar and Lionel Stephens. We also meet some of Sir Randolph's family: wife Minnie, daughter Ida and grandchildren Cicely and Osbert. A couple of expertly-sketched scenes are enough for us to get to know them a bit better: Gilbert Hartlip is a taciturn and humourless type, his wife Aline is a bored society lady whose boredom has led her to a string of affairs (most recently with Charles Farquhar, who she nonetheless doesn't seem to like very much) and gambling debts; Bob Lilburn is a dull and stolid sort of bloke whose wife Olivia, starting to realise how boring he is, is conducting a flirtation with Lionel Stephens; Tibor Rakassyi is a Hungarian nobleman who has his eye on young Cicely, and Reuben Hergesheimer is a middle-aged Jewish banker.
Below stairs, as it were, lurks another group of characters, including head gamekeeper Glass and his bright and ambitious teenaged son Dan, odd-job-man and occasional poacher Tom Harker, maid Ellen and footman John.
The shoot begins, disrupted briefly by the appearance of blood sports protester Cornelius Cardew. His arrival prompts some of the more self-aware and reflective members of the party (Olivia Lilburn, for instance) to wonder: what is all of this for? Not just the slaughtering of hundreds of pheasants, woodcocks, ducks and who knows what else, most of which will never be eaten, but the whole social circuit of endless weekends at country houses, meeting the same people, talking inconsequentially about nothing but whose country house you were at last weekend, the endless changing of clothes for rides in the country, drinks, dinner, the ruthlessly enforced social structures and strictures preventing you from ever saying what you really think.
Of course the date at which all this happens is no accident in this regard: it's barely nine months or so until the outbreak of the Great War and the start of the inexorable process by which all the stuff that underpins these people's lives will be swept away. We see an example of this in the book: young Dan Glass dreams of being a scientist and going to university to study: this sort of increased social and economic mobility among the "lower" classes is the beginning of the process that would bring the old class system down, the additional irony being that in offering to fund Dan's studies, Sir Randolph is helping to sow the seeds of his own demise.
Of course it would be very easy to draw the crusty country-house types as braying chinless buffoons, but Colegate is cleverer than that. Sir Randolph is a kindly old geezer and so is his wife Minnie (though slightly dotty), but hopelessly bound by notions of social position and duty. Similarly Olivia Lilburn and Lionel Stephens are reasonably sympathetically portrayed, though they are ultimately unable to act on their love for each other by the fear of being excluded from "polite" society (and, even more ultimately, by Lionel's eventual death in the war).
Sir Randolph considers any overtly competitive stuff like practising shooting or keeping tabs on your individual tally of kills to be a bit vulgar and not quite the gentlemanly thing; however this doesn't stop Gilbert Hartlip and Lionel Stephens and their respective loaders conducting a private battle. It is this rivalry which prompts the novel's climactic events, when, knowing he is trailing Lionel Stephens' tally of birds, Gilbert Hartlip reflexively takes a shot at a low-flying woodcock and hits Tom Harker in the face, fatally as it later transpires.
If you're seeing some similarities in all this to the film Gosford Park, you wouldn't be entirely wrong - Julian Fellowes admits as much in his foreword to the latest Penguin edition of the book (which, rather oddly, in its online version at least, misspells her name as "Isobel" throughout). The Shooting Party itself was made into quite a celebrated film in 1985, featuring all manner of heavyweight British actors. The book won the W.H. Smith Literary Award in 1981; my fairly brief list for this one goes: 1960, 1981, 1986, 2002.
I don't know whether that award carries any sort of cash prize along with it, but I can reassure you that regardless of that Isabel Colegate probably isn't short of a bob or two, what with having sold Midford Castle near Bath where she lived for many years to actor Nicolas Cage in 2007 for a cool 5 million quid. Strangely neither of the lazy drunken hacks who wrote the articles in the Daily Mail or the Independent at the time bothered to find out that "Mrs. Briggs" was actually a renowned and award-winning author (the Times managed to make the connection). An amusing footnote to the story is that Cage now seems to be selling up to finance the settling of a large tax bill from the IRS.