Fifty years ago biography wasn’t much interested in people like Mary Ellen Peacock Meredith. Her life was deemed “lesser”, although of course it didn’t feel like that to her. Born in 1821 to the poet Thomas Love Peacock, as a little girl she had bobbed in the shallows of second generation Romantic culture. Her dad had a lock of Shelley’s hair, and the family lived in North Wales, which was craggy enough to pass as “sublime”. Her mother, a local Welsh girl, went mad and joined that distinguished club of literary wives who were confined to an asylum. Mary would grow up to marry the novelist George Meredith, whose great masterworks Modern Love (1862) and The Ordeal of Richard Feverel (1859) are generally agreed to be a forensic account of their mutual misery.

Everything was in place, then, for Mary to become a perfectly serviceable footnote in other peoples’ stories. But in 1972 an American writer called Diane Johnson decided that this really wouldn’t do. Second wave feminism was beginning to throw the spotlight on all those over-looked women who had been “hidden from history”, especially literary history. Perhaps they’d been omitted because someone had decided, on no particular authority, that their poems or novels weren’t very good; maybe they’d been overshadowed by the men in their life who spoke or wrote with a louder voice. Finally, there was that select sub-group who had been redacted from the record simply because they were “bad” women about whom the less said the better. Mary fell into the latter thrilling camp.

In this short, spirited book Johnson sets about to rescue Mary from history’s purse-lipped amnesia. She gives us a stirring tale of a headstrong girl, brought up under the old licence of the 18th century but obliged to knuckle down to the stern realities of the new Victorian age. Except Mary never did. After all, a woman who jots down in her Commonplace book that “the wicked are in earnest and the good are lukewarm”, has what you might call an interesting point of view. Having recklessly married a dashing young naval officer who died saving someone else’s life, Mary Peacock found herself on the receiving end of an adolescent crush by the younger novelist George Meredith. She married him by mistake and then left him for the artist Henry Wallis, the painter of The Death of Chatterton (1856), that stunning oil painting which has been read as a eulogy for the extended Romantic age. Just to make it all weirder, the model for the sprawled-out poet-suicide Chatterton was none other than George Meredith.

It all caused a hoo-hah at the time. But Johnson’s ambition goes far beyond reheating stale gossip under cover of feminist scholarship. Her mission here is to make a generous gesture towards all the lesser lives who brush shoulders with history’s featured players. For instance, when writing about Meredith’s hated dad, she tells us that he took up with a servant called Matilda Bucket. “How one longs to know more about Matilda Bucket,” she writes and, just at that moment, so do we. There is a virtuoso sequence too where Johnson painstakingly goes through the letters of potential London landladies who have written in response to a newspaper ad of Henry and Mary Ellen seeking accommodation. What about Mrs Holloway, who promises that her Kensington property is “genteelly furnished”? Or Mrs Newbold, who explains that she is looking for “respectable persons as permanent inmates” but is probably able to overlook the fact that Henry and Mary are nothing of the kind? Finally there is the lady from Bloomsbury who is particularly proud of the fact that the watercloset is on the same floor as the bedrooms. Each of these little rills opens up a window on a whole new life that, Johnson suggests, is worthy of our full consideration.

Like much the feminist literary scholarship of the 1970s, The True History of The First Mrs Meredith bears an obvious debt to the critical work of Virginia Woolf, who, 50 years earlier, had asked pointed questions about what qualified as a “great” and thus write-able life, and what as an “obscure” and therefore ineligible one. In its jaunty generalisations about the 19th century, though, Johnson’s book claims clearest descent from Lytton Strachey’s satire Eminent Victorians (1918). In one striking passage Johnson wonders out loud whether Mary could really be bothered to commit adultery with Henry since it involved taking off so many layers of camisole, chemise, corset, petticoats, stockings and garters. But then, in one of her subversive self-cancelling footnotes, she informs us that all this biographical speculation about mid-Victorian women undressing for sex is probably beside the point when you remember that, at this point in history, nice women didn’t wear drawers.

• The True History of the First Mrs Meredith and Other Lesser Lives is published by NYRB (RRP £14). To order a copy go to guardianbookshop.com. Delivery charges may apply.