A Labour general election landslide brings hope and new opportunities for some and a chill threat to wealth, status and influence for others. Topical stuff, but this is 1945, not 2024. Lissa Evans’s seventh novel for adults introduces a family of minor landed gentry who fetch up on the other side of the war not only broke, but with the Lady of the house complaining that “she could almost have drawn a graph charting the slow decrease in the depth of curtseys she’d received”.

The Vere-Thissetts have been in this corner of Buckinghamshire since the early 15th century. Their home, Dimperley Manor, is a hotchpotch of turrets, domes, follies and other architectural whims and afterthoughts that now share consistency only in their comprehensive decrepitude. During the war, the house was requisitioned as a maternity hospital. It is returned to the family with “the scents of beeswax and wood-smoke displaced by the lingering smell of disinfectant”.

To make matters worse, the dashing baronet, RAF squadron leader Sir Felix, missing in action since 1942, is now declared dead. This leaves the family with two Dowager Lady Vere-Thissets in residence, prompting funnier than you’d think comic confusion over hierarchy and address. It also leaves responsibility for dealing with the mess to younger son Valentine – long in the shadow of his charismatic brother – as he returns from his own rather less trumpeted war service.

The first half of the last century has come to form the natural territory of Evans’s fiction. She has brought an amused eye and crisply fresh insight to well-worn moments of collective British history, from the suffragettes to the blitz. Here, her treatment of the immediate postwar world focuses more on a benign appraisal of posh and poor alike fumbling towards new accommodations than on the received national narrative of dramatic societal upheaval.

This is Evans’s first engagement with the upper classes, but into the mix she throws a more familiar figure in the form of Zena Baxter, a clever and efficient secretary “with barely a trace of a London accent”, who felt an instant affinity with Dimperley when she was evacuated there to have her baby. Zena stays on to help Uncle Alaric, who is writing an interminably arcane family history. He limits himself to just three glances at her a day, “the sort of gaze with which Constable would have viewed the Suffolk countryside”, he persuades himself, “an artistic appreciation of the harmony of light and form – bright, billowing clouds, smoothly rounded hillocks …” She inevitably finds herself assisting the affably overwhelmed Valentine as the bailiffs arrive and the masonry crumbles around them.

There is so much here that is culturally familiar: the immediate postwar era, the country house setting, and so on. However, Evans invests it all with a humane understanding of people, politics and the way that life actually works. She has a sharp appreciation of the almost imperceptible currents and ripples in domestic life and how they are affected by the vast oceanic sweep of social change.

Fun set pieces and a will-they-won’t-they romance sit easily alongside perceptive excavations of, unsurprisingly, class, but also, less expectedly, mental illness and disability; this elevates the whole beyond the cliches. In particular, Evans brings to the notion of marriage an almost Austenesque wit and moral rigour, to lay bare the complexities of pragmatism, passion, security, reputation, risk, cost and love as they attach to, mostly, women across the social spectrum. The overarching plot – what will become of the house and what will become of people attempting to find some sort of order after a period of extraordinary turbulence – is straightforwardly pleasurable, but the book really succeeds in holding its pervading warmth in constant tension with a genuine sense of financial, social and most of all emotional jeopardy.

Small Bomb At Dimperley by Lissa Evans is published by Doubleday (£18.99). To support the Guardian and the Observer buy a copy at guardianbookshop.com. Delivery charges may apply.