How hard it is to love Virginia Woolf after reading her thoughts about her cook, the woman who shared her home and the most intimate details of her life for 18 years. Nellie Boxall ran Woolf’s bath for her, emptied her chamber pot and brought her supper in bed on a tray when she was sick.

And yet, in Woolf’s diaries, this treasure is a “mongrel”, whose “timid spiteful servant mind” exhibits “the loathsome spectacle” of “human nature undressed”. When considering Nellie during a particularly bad row (her “little shifting greedy eyes”, her mind “almost incredibly without the power of analysis or logic”) Woolf’s revulsion verges on the physical.

After their innumerable spats, she feels “sordid”, “disgusted”, “degraded” by the transactions involved in dealing with a dependent – one tied to her by bonds of affection and loyalty as well as by money. “Have I ever felt such wild misery as when talking to servants? . . . Such a cancer, such a growth, such a disease as the poor are.”

This was written in 1930, just months after Woolf asked, in her eloquent assault on the male-dominated status quo in A Room of One’s Own: “Is the charwoman who has brought up eight children of less value to the world than the barrister who has made a hundred thousand pounds?”

The lofty ideals that inform this much-quoted question are impressive, but they aren’t easy to live by, not when there’s no electricity, gas or running water, Sitwell and Forster have dropped in for dinner – and wretched Nellie’s just given notice “for the 165th time”.

For there’s the rub: Nellie may have depended on Woolf for her wages (£50 a year in the late 1920s, when the writer was earning around £4,000) but Woolf – sickly, nervy, incapable at times of even feeding herself – depended on Nellie for practically everything.

It is that mutual dependency, and the messy emotions of shame, affection and anger that accompany it, which makes Mrs Woolf and the Servants so compelling.

Alison Light’s book is, in its own way, a far more revolutionary work than anything Woolf ever wrote. Herself the granddaughter of a kitchen maid, Light admits to starting out with a strong class bias, seeing domestic service as psychological and emotional slavery. Over the years, though, this assumption crumbled as she traced the lives of 20-odd Bloomsbury group housekeepers, nannies, cooks and gardeners, separating out the multiple Mabels and Flossies, endowing them at last with their own names and histories.

Nellie Boxall inevitably dominates the book because her doings between 1916 and 1934 were so obsessively charted by Woolf (who misspells her name as “Nelly” throughout), but she is not alone. One of the factors that made the mistress-cook relationship so fraught was the impossibility, for Nellie, of breaking away from her substitute family. Resigning in earnest would have risked the loss of her closest friend, Lottie Hope, whose 30-year career as housemaid and cook for Roger Fry, Virginia Woolf, her brother Adrian Stephen and her sister Vanessa Bell, shows how interlocked the Bloomsbury households were. For Lottie, a foundling, and Nellie, orphaned at 12 and out to work at 14, their employers were not oppressors or distant figures of authority, but part of a “click” to which they, too, belonged.

Earlier generations had carefully policed the distance between “them” and “us”, but for the self-conscious young moderns of Bloomsbury, servility would no longer do. Who, then, was the real boss in these households?

Not Woolf, it seems. Far from enjoying the responsibilities of an employer, she detested them, yearning for independence and privacy, for labour-saving devices that would not read her letters or make her feel bad about the weight of the coal scuttle. And although Nellie’s only weapon in their arguments was the threat to leave, she invariably, infuriatingly, withdrew it whenever her bluff was called. When, in 1934, the Woolfs finally sacked Nellie, rather than face her cries of “No, no, no, I will not leave you,” they simply upped sticks and fled, in agonies of remorse and relief, to their country retreat. Woolf’s horror at the scene – she felt “executor and executed in one” – quivers with guilty awareness.

The joy of Light’s book is that it works on many levels – as a gossipy Upstairs Downstairs narrative, as literary criticism and as a lively interrogation of the enlightened liberal cast of mind that Bloomsbury did so much to turn into today’s orthodoxy. We may recoil at Woolf’s frank loathing for the coarseness and stupidity of the masses, but how many of her intellectual heirs – the bien pensants and quangocrats of Westminster and the BBC – secretly share her gut feeling, lacking only her honesty of expression?

MRS WOOLF AND THE SERVANTS by Alison Light
Fig Tree £20 pp376
Buy the book here at the offer price of £18 (inc p&p)

Times Recommends

• The 100 Best Books of the Decade
• The Times picks the 50 best paperbacks of 2009
• The conversation: James Ellroy