Todd knew it as well as she did. “So I told Jennie, well, why not put him in for here, then? And she said, no, no, we couldn’t afford it even if they took him, and I said I don’t know about that, I’ve got a little bit saved up, and you never know, there’s bursaries and so on…”

He gave Walden a worried look, as if she might tell him off for his presumption. “Why not?” said Walden encouragingly. “That’s what the bursary funds are for.”

She found herself thinking, as the conversation went on, of Laura Kenning’s wry look in the moonlight: Why didn’t I have this? It was the same reason that Todd had not had this, an obvious, powerful, intractable knot of money and power and history, changing too slowly for most. “Have you thought any more about adult magical studies?” she said, which Todd seemed to hear as an abrupt change of subject, although in Walden’s head it was not. “The Open University offers a short course—I believe it’s all online these days—”

“Now, Dr Walden, show some sense,” said Todd, with lugubrious good humour. “Some of us have work to do.”

After lunch, she met Mark at Reception, the secure modern box that had been flung up to ruin the façade of the main school building in the nineties. The front desk was unmanned, and the glass-paned front doors were locked. Mark’s Audi pulled up, doing a rather showy turn around the wide gravel circle at the front of the school. He parked in a reserved space, jogged up to the doors, and waved at Walden through them. He’d swapped the good suit for jeans and a chunky jumper, with expensive trainers, all underneath a battered old Barbour that he almost certainly never wore in London. Walden wore the same clothes on Sunday as she did on work days, though in deference to the weather she’d put on a raincoat and wellies. She buzzed him in, and noticed as she did so that there was a little frisson of something inhabiting the electronic keypad that kept the door locked.

Walden frowned at it. That was the second new imp she’d encountered in three days. Yes, you expected minor possessions at Chetwood, but not this many, and not this quickly.

“Another one?” said Mark, peering over her shoulder as she murmured a banishment over the keypad. “Oh, it’s only an imp. What’s the harm?”

“I thought you were a security expert,” said Walden. “You don’t see a problem with stray demons in the security system?”

Mark laughed it off. “Fair, fair. Well, shall we? Where do you want to start?”

“Boundary sweep and work our way in, of course,” said Walden. She flipped the hood of her raincoat up. “Umbrellas are in the stand over there, if you didn’t bring your own.”