Poor Cassy. The Miss Austen of this novel’s title is Cassandra, Jane’s elder sister. She was to have married Thomas Fowle, but he died of yellow fever in 1797 on an expedition to the West Indies. Before he left, she vowed to remain faithful to him and, if he didn’t return, never to marry anyone else. It would be her undoing. In later life when she herself falls ill, Tom’s sister Isabella remarks: ‘It will take more than a fever to undo you, Cassandra.’ Yet, by Tom’s death, she was already undone.

The narrative moves back and forth between the 1790s and the 1840s. Towards the end of her life Cassandra is on a mission to find and destroy potentially disparaging letters written by Jane and by herself to Eliza, Isabella’s mother. By 1840 she is a demanding, decrepit old spinster, intent on safeguarding for posterity Jane’s, and her family’s, reputation.

Gill Hornby weaves a magnificent work of the imagination, a pastiche of Regency style and manners, fabricating a solution to a problem that has long mystified scholars. Why, as is suspected, did Cassy burn so much correspondence after Jane died? Hornby presents us with some of the letters that Cassandra discovers when Isabella clears out the vicarage at Kintbury and shows how she destroyed them. With a nod to the Luddites, Isabella’s annoyingly vigilant maid Dinah complains: ‘Then you turned up in the works with your spanner.’ Cassy finds ten letters ‘of danger’. How difficult it is, she reflects, ‘to control one’s family’s history’.

Yet Cassandra is driven. Her family is unlike any other. Her conviction is that ‘the Austens were remarkable… they were simply unique’. Jane’s reputation is Cassy’s passion. Suitors, for Jane, had been a distraction, including the eligible, landed Mr Hobday, ‘repulsed with an expert efficiency’. Jane had been satisfied in ‘her invented world’ of domestic drama, where she could show her profound ‘understanding of people, and a certain milieu’.

Hornby’s portrayals of Cassandra and Jane are tantalising. The elder sister is seen to be an obsessed, manipulative old woman, though seemingly well-intentioned. Dinah thinks her meddlesome; but she is a figure to be pitied for her lot in life. Jane is clever, single-minded, perceptive and sharply intelligent, her talent arming her against a world dominated by men.

All devotees of Austen’s novels will want to join Hornby, and Cassandra, in this enjoyable act of piety to Jane.