Frances Osborne may be married to the chancellor but, whatever the motivation behind her choice of literary subjects, it is plainly not a desire to alleviate media criticism that the present government is too posh. Her last book, The Bolter, was a biography of her great-grandmother, the scandalously five-times married and divorced Idina Sackville; also, according to Osborne, the inspiration for the delinquent mother in Nancy Mitford's The Pursuit of Love.

This time Osborne plunders her family's history for fictional ends. Sackville was the daughter of Muriel Brassey, whose great-grandfather had made a fortune in railways. By the start of the 20th century the money was running out but the family still lived in a magnificent mansion overlooking Hyde Park. The Brassey women, and Muriel in particular, were also prominent campaigners for women's suffrage. Muriel's story provides the inspiration for Osborne's first novel.

It is the spring of 1914 and 20-year-old Beatrice Masters is at a loose end. Though endless dinners and dances hold little appeal, she is hardly more interested in her mother's politics. Lady Masters is a suffragist, an advocate of peaceful protest and political pressure. Bea's Aunt Celeste  a passionate suffragette who believes only violent protest will force change, and whom Lady Masters has banned from the house  piques Bea's interest. One night, at Celeste's invitation, Bea attends a rally led by the notorious Emmeline Pankhurst. It is a decision that is to alter the course of her life.

Meanwhile, in the servants' hall, a new maid has joined the household. Grace Campbell, a bright girl from Carlisle, had hoped to gain a position as a secretary but instead is forced to accept a job with the Masters as a third housemaid. Grace is an engaging character, untrammelled by the clichés of the upstairs, downstairs tradition. Her family were once mill owners who, not unlike the more aristocratic Masters, have fallen on harder times. Being further down the social scale, they cannot so easily disguise their straitened circumstances, but they remain fiercely respectable. Grace's mother keeps a silver spoon in a box on the mantelshelf: "To sell it, Ma says, would be selling the fact that my ma was lady enough to own a silver spoon." Grace is educated and a skilled typist, but her thick northern accent deters potential employers. It is not equality at the ballot box that she yearns for, but equality of opportunity.

The novel is told from the alternating points of view of the two women. Grace has a distinctive and likable voice, rich with lively idiom and often very funny, though it is at times hard to follow the whimsical slippage from the third person to the first as her thoughts intercut the narrative. Beatrice is less well rounded. In her historical note Osborne describes Muriel Brassey as "tiny in stature, but huge in character", but she struggles to capture this vivacity on the page.

It is a shame, then, that, as war breaks out, Osborne rather abandons Grace's story to follow Beatrice to France. The scenes on the western front are among the best in the book, but fail to make a whole of the novel. The over-long first half could have done with some judicious editing: once the war begins, and the story accelerates through the next 10 years, too many aspects of the plot turn out to have no consequence, or are simply forgotten. Osborne has a pacy style and an assured grasp of period, which make Park Lane a breezy read, but the spirit of the real-life Muriel remains tantalisingly out of reach.

 Clare Clark's Beautiful Lies is published by Harvill Secker.

There are worse things a politician's wife could do than write a book or two. They could tweet sickeningly that their busted flush is "My hero" while sucking up to supermodels who assault their staff. They could roll in the mud with crystal-wielding bedlamites in the vain hope of seeking "rebirth". Compared with such cretinism, surely a bit of scribbling is a safe way for a political consort to spend their time?

But every book hides a backstory. Mary Wilson's poetry may have indicated a woman left cold by her husband's permanent froth over the supposedly imminent white heat of technology. Norma Major's book about opera perhaps suggested a boredom with her apparently humdrum hubby, little knowing that he had performed the Ring Cycle thrice nightly with his future minister of health. And now George Osborne's wife, Frances, has written a novel that chronicles the upsetting of the pre-first world war social hierarchy  and in which the hero is a Labour MP.

Though I am a modern chav and Mrs Osborne an old-fashioned posho, I must say I winced in a manner that would have made FR Leavis proud as I took in, cross-eyed with sheer molten outrage, the first line of this book: "Grace can just see the bedroom door handle ahead of her." Maybe I'm just a middle-aged fuss-bucket, but I hate the present tense used in any representation of history, be it fact or fiction. And it doesn't get any better  the style is vile; unlike her pasty-persecuting, pensioner-pinching spouse, Mrs Osborne is far from prudent with her resources and rarely uses one word where a hyphenated-horror will do. Door handles are "night-cold and turnip-big", invariably leading to "weigh-a-ton curtains".

The wretched housemaid, Grace, while pertaining to hail from Carlisle, rabbits away in her own head in a dialect that resembles nothing so much as that of Patrick Hamilton's appalling Joan Plumleigh-Bruce speaking "Oirish" to her poor Irish servant, Mary. Indeed, J P-B fancied herself as a great student of history, when in fact merely reading anything about Marie Antoinette she could get her hands on, and after only a few chapters, that's what this book made me think of. It's as if Joan Plumleigh-Bruce had written a book about the suffragettes.

There is a strong whiff of the midnight oil coming from this novel and you can imagine Mrs Osborne cramming like crazy at the British Library to get all the little period details just so. But at a time when there is so much brilliant, vivid history available via radio, television and non-fiction books, it seems wildly pointless to trudge through this era one more time at great fictional length unless a bunch of unforgettable characters has been created to dance us down the centuries. Seriously, I've come across paper dolls with more depth than this crew.

An alternative title might have been "In My Lady's Chamber", as the shadow cast over this book by the brilliant television series Upstairs, Downstairs (the original, not the recent rotten revenant) is considerable, throwing Park Lane's flimsy characters and predictable plot into even grimmer relief. It's hard to make an account of the righteous, violent struggle for women's suffrage read as boringly as a budget, but Mrs Osborne pulls off this feat quite seamlessly.

There isn't even the consolation of a couple of Dirty Bits to break the monotony. I thought things were heating up when, at a rally addressed by Mrs Pankhurst, the well-born heroine finds that "her breasts are being squashed flat against whosoever is in front of her" and feels "something hard and round-ended is digging into her back". But it's only a boring old club, being wielded by a suffragette. I'm way past the age of looking for rude bits in books and it's a measure of this one's dreariness that I was forced to grasp at the hope of tawdry titillation in this way.

AN Wilson wrote an astoundingly good, astonishingly scathing piece about Downton Abbey last year in which he accused the show's creator, Julian Fellowes, of glorifying an ordering of society that was hateful in reality. This is just more of the same  and there is something repulsive about a book that celebrates a pivotal moment of social progress  votes for women  by the wife of a man who serves in a government that contains more well-born nobodies than any since the second world war, men who would probably not have attained such status had they had to get there on their own merit rather than been given a leg-up by their expensive educations and extensive crony network.

Though profoundly unsexy, this book left me feeling somewhat grubby for having read it. It invites the reader to conspire in fetishising their own oppression  a bit like Fifty Shades of Grey, I imagine, but without the cheap thrills. Night-cold, turnip-big and weighing a ton, I suggest you give this book the swerve and spend the money on pasties instead. Stodgy and full of mechanically recovered matter though they too may be, their consumption will only take up minutes rather than precious hours of your time.