Terry received Sally-Anne’s letter that evening, several hours before Lord Voldemort’s return was publicly acknowledged by Minister Fudge. If Terry did not reply, that was probably because he knew that owl service was insecure – a factor that Sally-Anne only realised later.

Sally-Anne officially spent the year 1996-7 working in her mother’s bookshop, and together they did indeed build up a modestly profitable business. The shop provided a convincing front for the family’s undercover activities. While Sally-Anne was still not allowed to do magic out of school, her work in the shop gave her mother time to front down Dementors. It became quite well known that the unseasonably cheerful atmosphere that so often invaded the western Midlands was due to a bushy-tailed squirrel Patronus; but the Death Eaters never traced the squirrel to Julia Slater.

This was just as well, for the Slater home was a hive of rebellion. The Order of the Phoenix sometimes had wind of whom the Death Eaters planned to attack next, and nine times in as many months, they whisked a family of Diagon Alley traders into hiding before the Death Eaters arrived. Although the shops were forlornly boarded up, the proprietors found a safe refuge in Sally-Anne’s house until they could escape abroad.

Raymond Slater never complained about the risks to his family. “It’s all of us against this No-Name-Wizard, whether we’re magical or not,” he said more than once. “I’m glad we managed to save Mr Hopkins and Mrs Bones. Sally-Anne couldn’t ever again have looked Wayne or Susan in the eye if we’d refused to do that much.”

In the summer of 1997, the Ministry decreed that all school-aged wizards must return to Hogwarts, so Sally-Anne began her N.E.W.T. courses after all. She was now a year behind Hannah, Susan and Megan, but they were always together outside of lessons. As a grim and constant reminder of the war, none of them heard from Sophie, who had been captured by the Snatchers.

Sally-Anne covertly defied the Carrows from the first by refusing to “mean it” when she pretended to cast the Cruciatus curse. When she heard that Neville Longbottom was openly disobeying them, she was one of the first to seek him out and volunteer to join the resuscitated Dumbledore’s Army. She was personally responsible for destroying all of Alecto Carrow’s third-year teaching notes and she became adept at all manner of unlocking and releasing charms when it came to rescuing victims. But it was her sister Ella-Jane who excelled at sneaking Billywigs and Doxies into Professor Snape’s office, while Molly-Rose specialised in daubing seditious graffiti on the walls.

All three Perks sisters were among those who fled to the Room of Requirement in the final few days of Voldemort’s rule, and Sally-Anne remained to fight in the final battle.

After the war, Sophie was released from the Snatchers’ dungeon, only to find that the Death Eaters had destroyed her whole family. In a matter of weeks, she married Ernie Macmillan and went to work for Woolman’s, the wizarding textile industry. The other girls had an easier time. Susan was able to work for her mother, who returned from exile within days and resumed her architecture business. Megan put in the winning bid for Florean Fortescue’s old ice cream parlour and resuscitated it under the new name of Y Draig Rhudd. Hannah cooked and managed in The Leaky Cauldron, where she was so efficient that old Tom soon passed the business on to her. They were all settled in their new lives by the time Sally-Anne finished her N.E.W.T.s.

Sally-Anne continued to spend many hours a week in her mother’s bookshop, which was recommended in all the education supplements, but in her spare time she experimented with mixing various cleaning agents. She soon developed a whole range of new and highly efficient household cleaners, polishes and disinfectants, which she was able to market both to Skweekerkleen’s and – under discreetly altered labels – to a few Muggle outlets, which brought in money for the wizarding economy.

Sally-Anne’s siblings and stepsiblings all lived happily ever after. Ella-Jane became a private investigator and devoted her life to snooping around pure-blood divorces and frauds. She successfully avoided men until the age of twenty-nine, when she married a Muggle RAF officer; they named their children Leon and Boadicea. Molly-Rose worked as an editor for WhizzHard Publishing. She eventually pulled her nose out of the books for long enough to marry Luke Brocklehurst (the same Cousin Luke who had attended Cressida’s Christmas party), and their children were Paracelsus and Hypatia.

Xavier’s thespian pretensions were even less successful than his father’s; in the end he had to marry Mr Parkinson’s granddaughter in exchange for a job in Parkinson’s Real Estate – and the less said about that firm, the better. Flavian Perks never did much work, but Cressida’s shop in Knockturn Alley was a sensational success. In case you were wondering, she sold erotic aids.

The legal wrangling about Christopher Slater’s custody arrangements stopped on his sixteenth birthday, but the financial strain of paying off the lawyers’ debts lasted several years longer. Fortunately, Raymond was promoted to middle management at the metalworks. It would appear that neither he nor Julia resented the pressures of parenthood, because after their own offspring were off their hands, they took in a long string of foster children.

Christopher became a computer salesman and never told his Muggle relations that his stepfamily were witches. But Jeremy, who trained as a civil engineer, met a number of Sally-Anne’s wizarding friends, and in due course he married the locospector Mary Fenwick. The Honeysmooches set up Ursula as a partner in their perfume business, and with this financial security, she was able to entice Adrian Pucey into marrying her. They had two sons. Cecilia made a nuisance of herself around the Witches’ Institute for several months after failing her N.E.W.T.s, and when that became boring, she and her friend Pansy Parkinson set up a small business selling cosmetics and colour analysis. Cecilia married Stan Shunpike (poor Stan!), and they had two daughters.

Terry Boot remained on cordial terms with Sally-Anne for as long as their paths naturally crossed, but they did not try to be close friends again. He passed all his N.E.W.T.s on the first attempt and was able to train as a healer; but instead of working for St Mungo’s, he joined a Muggle medical mission in Burkina Faso.

Sally-Anne was married at the age of twenty-two to the mysterious S. Capper. She had already met him at Hogwarts, of course; and she met him again during the war, because he was apprenticed to the securities expert who set up and maintained all the advanced securities on the Slaters’ home. But it was only after Sally-Anne was properly launched as a successful businesswoman that the time became right for her to identify Simon Capper as her soulmate. They had four children. Ella-Jane and Molly-Rose both complained about the Cappers’ boring choice of names (Edward, Geoffrey, Rosamund and William), but Sally-Anne said that she preferred names that did not draw attention to themselves in the “real world”.

The enchanted glass shoes were not wasted, because Simon took Sally-Anne dancing on many a Saturday night, right up until the year when their daughter took the shoes with her to Hogwarts. Aunt Odette said that the three charms would not be compromised because the moral ownership had been properly transferred in a free donation.

You might be wondering whether anything further ever happened between Sally-Anne and God. As the answer to that question is not part of this story, the reader may decide.