I had come to the Staffordshire Record Office to try to piece together the ghost of a story - a story in which a vulnerable servant fell foul of an immensely powerful regime.

I'd been tipped off about a bundle of letters buried within the vast archive of the Sutherland estate concerning one Mrs Doar, housekeeper to the first Duke and Duchess of Sutherland - and her brutal ejection in 1832 from Trentham Hall, the family seat at Stoke-on-Trent.

This sounded perfect material for my book The Housekeeper's Tale. One working woman - loyal, obedient, faceless - enabling the sumptuous lifestyle of Britain's wealthiest, most influential and most detested family of the day. I was particularly keen to get to the bottom of Mrs Doar's disgrace, as this story had contemporary resonance: mention the Sutherlands and there is still a visceral reaction. For all their tentacles of influence throughout the British Isles - from canal building to art collecting, state diplomacy to herring fisheries - they are remembered in Scotland for one thing only: the Highland Clearances.

Between 1811 and 1820, about 15,000 crofters were forcibly removed from their Sutherlandshire homes, opening up thousands of profitable sheep-farming acres. The statue of the 1st Duke near Golspie - "The Mannie" - is regularly vandalised to this day. What extra perspective could Mrs Doar's tale throw on this family's notoriety?

The story unfolds in 1832, the year of the Great Reform Act. The franchise in Scotland was extended from 5000 to 60,000 voters: finally, the people got to exert some influence on how their country was run. At this time, George Granville Leveson-Gower was one year away from being made Duke of Sutherland. He and his wife, Elizabeth, were then known to Mrs Doar as the Marquis and Marchioness of Stafford ("the M" and "Lady S" behind their backs).

The Sutherlands had five housekeepers. Like pawns on a chessboard they were ranged across the country: Mrs Spillman sat at Dunrobin Castle near Brora, in the far north-east; Mrs Cleaver at the southernmost extreme, West Hill in Wandsworth, Surrey. In London, Mrs Galleazie reigned over Stafford House, scene of much entertaining. Mrs Kirke presided over the new hunting lodge, Lilleshall Hall in Shropshire. Mrs Doar sat plumb in the middle as keeper of Trentham Hall, Staffordshire.

As head housekeeper to Britain's richest family, this was one of the most senior posts of the time for a woman (though her wages, at around £30 a year - £1300 in today's money - were on the low side). But in the annals of the Sutherlands, Mrs Doar barely figures. And if you want to track down her ghost today, you will find that the house she ran is gone. Just a grassed-over bumpy footprint remains, overlooking the vast formal gardens and the lake. Yet there is a palpable sense, in the audacious scale of that lake, of this family's tremendous self-regard. The house is gone, but an atmosphere remains.

In the archive office I turned first to a bundle of correspondence from Elizabeth, Marchioness of Stafford, to learn what kind of a woman she was to work for. The daughter of the 18th Earl of Sutherland, she was born at Leven Lodge near Edinburgh in 1765, and inherited the land and titles in infancy following the death of her parents. I knew that the Highland Clearances had been done in her name - that on witnessing the starving tenants, the 19th countess of Sutherland is said to have observed that "Scotch people are of happier constitution, and do not fatten like the larger breed of animals". I'd read a letter from 1815 in which she asks her chief agent, James Loch, "to encourage Sellar in trouncing these people who wish to destroy our system … I do hope the aggressors will be scourged". (Sellar was a notorious agent put on trial for his needlessly violent evictions.)

But what of her private side? At first the letters confirmed my prejudice. Mrs Doar's mistress was indomitable, the sort who mannishly pooh-poohed physical danger - such as when she travelled by paddle steamer up the North Sea coast to the Moray Firth in October 1831. "A delightful voyage," her gold-edged letter to her husband Lord Stafford began; "I triumphant riding in the storm … All sick except myself who was famished & ate roast beef like a Dragon. It is very odd that though tiresome enough it has not frightened me at all." Her maid Betty, meanwhile, was "half dead".

Then I found another letter. She wrote again to her husband after touring her Sutherland estate (which covered two-thirds of the county), describing first the domestic set-up at Dunrobin Castle and then at Trentham Hall with surprising appreciation and fondness for her housekeepers. At Dunrobin, all was "in perfect order, Mrs Spillman exceedingly active & happy but finding great difficulty in breaking in Cook maids". At Trentham: "I found Doar with everything ready for me & am to have a Partridge for dinner with a boiled Fowl in addition, some fish & an apple tart. Such good bread & butter!" This vignette gives a different picture of the dragon-like Marchioness - by this time a stout 66-year-old, known by gossips as "old Mother Stafford". For all her "princessly" airs, she was not above noticing - and praising - a good piece of bread and butter.

So what went wrong for Dorothy Doar? I discovered her in a bundle of dry estate correspondence between chief agent James Loch, based in London, and the Trentham land agent, William Lewis. On April 2, 1832, a bombshell shattered the life of this exemplary housekeeper. Here is the first letter from Loch to Lewis: "Her Ladyship desires me to say that Mrs Doar has announced her pregnancy - and that after deliberating very maturely on the subject she has written to her to say she cannot stay. I am quite certain that her determination is correct and I really gave it every consideration. It would be a bad example to others, and a Housekeeper who has Maids to look after should not be bearing children even to their husbands."

Intriguingly - and most unusually for a housekeeper - Mrs Doar was married. Her husband,

jobless, lived outside the estate walls. Even more unusually, the couple had a young daughter, sent away to school at great expense.

"Lady Stafford wishes you to see Mrs Doar as soon after you get this as you can and to soothe her," Loch continued. "Her Ladyship laments this circumstance exceedingly, as I must say I do, as Mrs Doar was a most excellent and zealous and faithful person and who did her duty fully, amply and conscientiously. Lady S wishes you to say so to her."

It had been a hard decision, even for a tough old Marchioness - and Loch was impressed by her genuine regret. He added in a postscript: "She does not wish her [Mrs Doar] hurried away by any means."

By next day's return post, Loch received a letter from a distraught Dorothy Doar, incoherent and illegible. It is the only letter to survive in her handwriting, and it reads as a howl of despair. Mrs Doar was not expecting to be sacked for having a baby. She had asked her mistress for six weeks' leave, promising to then put the child "out to nurse" so it wouldn't "interfere with my business". The Staffords were barely at Trentham for six weeks a year.

"I hope and trust Sir you will be my friend and prevail on my Lady to allow me to stay," she begs Loch, "if it's only for a short time as God knows what will become of me … I assure you at this time my heart is almost broke. I have been upwards of 14 years in the Marquis of Stafford's family and it grieves me much, very much indeed to leave it - indeed Sir to describe to you the distress I am in would be impossible."

Loch - damned by history as the intransigent, inhuman architect of the Highland Clearances - was an exceptionally busy man. He had been with the Staffords for 20 years, auditing the landed estates in Scotland, Staffordshire and Yorkshire. He was also a Whig MP for Wick Burghs, and was immersed in the Reform Bill excitement. Mrs Doar's troubles might have seemed a small irrelevance to Loch, but this was not how he treated them. Hearing from Lewis that the housekeeper seemed "in very great distress" and had "not saved a single shilling but is desirous of setting up a little shop to sell Groceries & confectionary goods", Loch turned his mind to extracting some good from this unfortunate case.

This is all the more extraordinary when you consider the headline news of the time. A cholera epidemic had recently arrived at the British ports: 3000 were to die in Glasgow and 450 in Paisley, while in London the postman had to throw letters over the high brick wall of Stafford House. The Reform Bill, blocked by the House of Lords, had Britain teetering on the brink of revolution. In the disenfranchised industrial cities, windows were being smashed, gas pipes ripped up and meetings broken up by mounted police.

Despite this febrile atmosphere, William Lewis set about finding an estate property that might do for Mrs Doar's little shop. On April 6, Loch replied to his letter - three days before the Reform Bill's first night debate in Parliament. "Your idea for Mrs Doar is upon the whole approved of," he wrote; Lord Stafford would help with start-up costs.

It was a generous offer - and it was the final offer. "Both Lord and Lady S are very sensible of Mrs Doar's being a very faithful servant - but it is quite impossible in such an establishment to permit of her breeding." Lewis was to help set Mrs Doar up in this shop straight away. "Of course her own health and situation are to be first consulted," wrote Loch, "… and let it be known that she has her Ladyship's support and that she goes on good terms."

So much oil poured on to troubled waters, so much soothing and praising of Mrs Doar's talents and loyalty. And yet still she was to be let go, rather than granted six weeks' leave.

There is an ambivalence, here, in what we learn about Lady Stafford. She is surprisingly maternal and caring. And yet she is also ruthless. She loses our sympathy by dismissing the pregnant Mrs Doar - but she does it with delicacy. And shocking as it might be to modern sensibilities, this was an accepted 19th century norm: domestic servants were not supposed bear children.

Trentham Hall's housekeeper then did something desperate. "I am this moment told Mrs Doar has packed up eight dozen of sweet wine to be sent off," wrote Lewis to Loch with irritation on May 9. "Is this allowed? Mrs Doar has not pleased me these last few days, for I think she does not estimate properly the great kindness shewn her by the family and thinking she ought to be continued."

Dorothy Doar, now nine months pregnant, continued to pack furtively into wicker hampers items from her store cupboards: mops, brooms, tablecloths, tea, sugar, candles, soap. She had no savings. She had a daughter at school, a feckless husband, rent due on the family lodgings and a baby due in a matter of days. She had served this family for 14 years, through the reign of three kings; and now, abruptly, she was to be shown the door. And what was it to them anyway, a handful of mops and dusters? Her Lord and Lady ate breakfast off solid silver plates under paintings by Holbein and Gainsborough.

On May 28, the housekeeper's hampers were forcibly broken open and her "depravity" exposed. What shame she must have felt. This once "zealous" servant was ejected immediately. Lewis accompanied her to a nearby inn and found her a room, on account of the rain (privately, though, he was horrified: "Who could guard against such a Devil?"). Loch, who had refused to believe bad of Mrs Doar, sent Lewis a measured letter to be read out to her. The Marquess and Marchioness of Stafford, he wrote, "desire me to express their severe disappointment that a person in whom such confidence was placed for so many years, should have behaved so little worthy of it".

There would be no little shop, now, for Dorothy Doar. There would be no country house employment, either. The family's future would be harsh, probably ending in the workhouse.

As the Clearances suggest the Staffords were a ruthless pair - their minions too. Yet Mrs Doar was deliberately spared the harsh severity of the law. "If he shall purloin, or make away with his master's goods to the value of 40s it is felony," states one servants' rulebook, "and he shall … on conviction, be transported for 14 years."

The Staffords also made a point of praising Trentham's agent, Lewis. He had "maintained their interests - yet without any unnecessary vigour or hardship".

Loch (who would remain an MP until 1852) was "only thankful that it had led to nothing worse or more criminal". I can see him shaking his head, baffled that Dorothy had 'let him down' in this way, "I say so most sincerely".


The Housekeeper's Tale is published by Aurum Press, £20; also available as an e-book. Do you have a housekeeper's tale? Visit www.housekeepers-tale.com with your story