In Austen's original, the servants are lightly mentioned. Here it is the Bennets who are almost incidental.
There are balls and dinners aplenty, Elizabeth and Mr Darcy fall in love, Lydia absconds with Wickham - but these events are felt as ripples down in the kitchen where the servants have their own hopes, dreams and tragedies to occupy them.
Spirited Sarah is an orphan, plucked from the workhouse for a life in service.
Her future seems to have no hope of happiness. Then, suddenly, a new servant joins the household, James the mysterious footman. As she empties chamber pots, scours pans and curls the hair of the Bennet girls, Sarah finds herself increasingly fascinated by him.
Meanwhile young, innocent Polly is easy prey for the ghastly Mr Wickham. And Mr and Mrs Hill struggle with their own well-buried secrets.
Carefully crafted to dovetail with the original, Longbourn is still very much its own book. Baker's prose shines. She shares Austen's keen powers of observation, her attention to detail and ability to evoke characters to shape a story.
But her style is far from imitative. This book is all grit rather than social satire and it takes us places Austen never did - not only below stairs but also into battle.
Baker is a UK novelist whose own family a few generations back were in service.
Her previous books have had low-key releases but this one sparked a bidding war and a movie is already planned. As a novel it would have worked without the Austen connection; houses all over England in that era had the same sort of set up.
But without the presence of the Bennets, hapless William Collins and Mr Darcy striding about haughtily to give it literary celebrity status, it surely wouldn't have created such a splash.
I think Longbourn will please most Pride And Prejudice fans. It adds to the story rather than parasitically feeding on it and the different perspective makes it worthy of a retelling.
Even those who don't know the much-loved original, or read it so long ago they barely recall its plot and characters, will find this book independent enough to be completely engaging.