It’s hardly a likely setting for an epiphany, a party full of the rich, the richer and the richest, all ghastly, in a marquee shrouded in ‘wastes of grey velvet’. Not exactly where you’d expect a person to begin to pull himself out of the ‘malarial swamp’ of his self-disgust. But Some Hope is the final volume in Edward St Aubyn’s seductively readable trilogy, and as with the first two (Never Mind, in which incestuous child abuse occurs within a ‘civilised’ English family, and Bad News, in which the protagonist combines collecting his father’s ashes with a monumental two-day drug binge) it is the incongruities that make, ultimately, for a very satisfying whole.

St Aubyn’s prose is as sure as ever, his images sharp and telling, his psychological insights penetrating, especially when he is writing from Patrick’s point of view. As he battles with his inner demons, the now drug-free Patrick faces full-time lucidity – ‘an unpunctuated stretch of consciousness, a white tunnel, hollow and dim, like a bone with the marrow sucked out’. He is ‘swept away by a landslide of regret as the kettle boiled or the toast popped up’. The hypnotic memory of his father draws him ‘like a sleepwalker towards a precipice of unwilling emulation’.

As the narrative moves towards the climactic party, Patrick too progresses towards a climax of his own – a confession to his best friend, Johnny, over dinner, of what his father did to him. This is a scene all the more convincing for being strangely anticlimactic and almost farcical, with its constant interruptions from an oversolicitous waiter who excuses Patrick for snapping at him when Johnny asks, ‘Can you forgive him?’ The ‘catharsis of confession’ may have eluded Patrick, but it paves the way for his later realisation that ‘only when he could live with the ambivalence of never forgiving his father for his crimes but allowing himself to be touched by the unhappiness that had produced them … could he be released …’

To form the silly, trilling counterpoint to Patrick’s basso profundo an army of extras is drafted in, the guests at the aristocratic neanderthal Sonny’s birthday party. As bit players upon Patrick’s stage, they are not fleshed out so much as brilliantly sketched in, like drawings by Marc or Osbert Lancaster. There’s the nanny who thunders ‘No sweets in the nursery except on Sundays’, the bevy of lithesome, bitchy young women looking for rich husbands, the suave men about town who talk in well-honed aphorisms, the grande dame who comes out with vacuous but oh-so-amusing observations (‘The Great Barrier Reef is the most vulgar thing I’ve ever seen. It’s one’s worst nightmare, full of frightful loud colours, peacock blues and impossible oranges all higgledy-piggledy while one’s mask floods’) and sundry others. The pièce de résistance has to be the stunningly accurate (well, according to what is said about her) portrait of Princess Margaret as party guest – stupefyingly tactless, manipulative, censorious, flirtatious, charming and occasionally witty, all at the same time. The set-piece dinner party at which she humiliates the French ambassador for flicking venison gravy upon her ballgown, while other guests simper and ma’am, is sheer heaven.

At the start of Some Hope, Patrick Melrose is ‘desperate to escape the self-subversion of irony and say what he really meant, but really meaning what only irony could convey’. Happily, the author has no trouble in harnessing the beast to his own ends. St Aubyn’s novels are short, precise, ironic, and all the more remarkable for packing so much in.