Servants: a downstairs view of 20th-century Britain, By Lucy Lethbridge

In hindsight, life in service has become more visible than when our forebears washed and waited.

Given that servants were people who traditionally didn't have a voice, there are an awful lot of books about them. Historically, people didn't read about servants – they had them, were them, or were busy doing something else. But after a century that saw service change beyond recognition, torn apart by two world wars, class upheavals and technology, we can't get enough of what the butler saw and the housemaid did.

Perhaps it's a case of "there but by the grace of God go I". As Lucy Lethbridge reveals in Servants, in 1900 domestic service was the single largest occupation in the country. Were we all transported back to the start of the 20th century, it would be to a life on the wrong side of the green baize door for many. No wonder we're so interested in the strange and strained relationship between employers and servants.

"The keeping of servants was not necessarily considered an indication of wealth," explains Lethbridge. "For many families it was so unthinkable to be without servants that their presence was almost overlooked". Demand for servants was high at the start of the century, but service was a double-edged sword. For servants in rich households, meals might be "beyond anything they could possibly have imagined before". When Rose Gibbs, a scullery-maid in Surrey, "saw the food laid out in the servants' hall, she 'just stood and cried, wondering if my mother and father had any food'." However, "a single maid in a small household would need to carry an estimated three tons of water a week".

For some, there was a certain cachet to service. Lethbridge writes about girls whose fathers refused to let them work in a shop, because they would have to serve everyone, rather than gentlemen. But there was also an understandable reluctance to enter a life of drudgery. Journalist Elizabeth Banks went undercover as a housemaid in 1892 to find out why "many girls would do almost anything" rather than "cleaning someone else's house". A near-destitute seamstress explained: "I prefer to keep my liberty and be independent".

As the First World War approached, "it became increasingly difficult to convince girls that paid housework had moral superiority". The working classes were becoming politicised and "factory work offered resistance" to deference. Still, "servants were scorned" as "despised representatives of class betrayal".

There are fascinating passages on unusual areas of service, such as the Universal Aunts agency. Set up in 1921, this was an ingenious response to the glut of "ladies of irreproachable background" who were low on funds and whose marriage chances had died in the trenches, and to the needs of employers finding it harder than ever to find servants.Lethbridge also pinpoints when our interest in the secret life of the servant was sparked. "By the 1960s the era of the country-house servant had assumed an anthropological distance," and several former servants wrote autobiographical bestsellers. She also acknowledges that "No contemporary cultural phenomenon has laid the template of our idea of below-stairs life quite so completely as the BBC television series Upstairs, Downstairs."

It's sobering to read that "the modern innovations that removed visible labour from the good life are still underpinned by an unseen army of workers, a high percentage of them migrants". We might enjoy reading about the hard, filthy work that our great-grandparents undertook, but we have absolutely no desire to get our hands dirty.