First the bad news: Nina Stibbe’s new novel does not feature Lizzie Vogel, the engaging narrator of the trilogy that made her name as a comic novelist after she’d first published some extremely funny letters written during her stint as a nanny in a north London household in the 1980s. Man at the Helm (2015) is the novel Dickens lacked the generosity to write, in which tribute is paid to the creative value of a chaotic childhood presided over by what the conventional world calls an unfit parent. The two which followed covered just a year of Lizzie’s teens and early twenties. The fact that our beady-eyed chronicler remains on the threshold of adult life ensures an atmosphere of optimism, despite the dark strain of jeopardy running through each of the books.

In her fourth novel, which spans the years 1990 to the present, Stibbe has set herself an altogether more challenging task. The backward-looking narrator, Susan, is a garrulous middle-aged wife and mother with too much spirit to identify as disappointed and too much disappointment not to be, just occasionally, disappointing to the reader. The setting, as always, is the Midlands. Susan lives in a modern house in an imaginary town called Brankham, next to the campus of the University of Rutland, where she works in the office of the vice chancellor.

Years earlier she was employed at The Pin Cushion, the town’s haberdashery, and became friends with Norma, the eccentrically dressed and coldy opinionated daughter of its owners. There are signs that they were mismatched from the start. Even as a young woman Susan is a compulsive conversationalist of the one-thing-leading-to-another-by-a-roundabout-route school. Her boyfriend Roy, the marketing manager of the local golf club, ‘soon gets the hang of pointless conjecture’, but Norma is full of red lines and cuts Susan short when she starts to tell a story about a dog or a dream. When Susan becomes pregnant and drops out of her degree to marry Roy, Norma makes it clear that she thinks her friend is a loser, and the stage is set for three decades of undermining. Norma marries for advantage, twice, and never ceases to take a dim view of Roy, or of Susan’s daughter Honey, though she hurtfully makes a protégée of clever Grace, Roy’s daughter from a previous liaison. Susan sees that Norma is a piece of work, but the insufficiencies in her marriage keep her from walking away.

A technical problem occurs in a novel when the person who can’t stop talking is the narrator. In one of those suddenly ugly scenes that erupt in the most peaceably moribund of marriages, Roy taunts Susan about how Grace begged her to stop talking on their very first meeting. I defy any sensitive reader not to wince at this cruel reminder, while also feeling a bit team Grace.

It is a relief to Susan when Honey, who has trouble fitting in, goes off to university:

I thought she’d never leave, like Doris Lessing’s son, Peter, who lived with her his whole life and was with her when she heard she’d won the Nobel prize for Literature. The image of him alighting from a taxi holding an artichoke and a string of onions had haunted me. It was so odd and unabashed, so Honey.

This is so Stibbe – the seemingly inconsequential retention of an image seen on the news, which is both revealing of Susan’s anxiety and pulls together stray clues about what Honey is like. ‘This is precisely why I never wanted children – you just don’t know how they’re going to turn out,’ says Norma, tone deaf as ever, when Susan looks to her for reassurance.

Norma is not given an inner life at all, just surface oddness and over-arching ambition. She is a sort of Widmerpool in how she navigates the world, except that Widmerpool didn’t have a Susan. Elena Ferrante has lifted the lid on the degree to which some women live imaginatively inside the lives of their close female friends. But this is something else: an account of what it is to live alongside a friend who has long since ceased to qualify for the title but is somehow part of the story, and always will be.