“Just email us asking for the item to be made available.”

“I will right now.” My eagerness had already brought me trouble, and I was anxious that it shouldn’t twice. “I’ll email you personally, shall I?”

“If you wish. Address it to Derek Lister.”

“And I’d appreciate it if you wouldn’t mention all this to anybody else.”

I had Julia more in mind than Roy, but couldn’t say. “Not necessary,” Lister said.

Did he mean informing anyone, or had my request offended him? Asking might antagonise him, and I ended the call so hastily that I almost neglected to obtain his email address. It took me some time to compose a wary message. Further to our phone discussion, this is to confirm my request to consult Lumen Scientiae in your archive on Thursday. Sincerely, and I had to tell myself there was no reason why Julia should see the email. Pa, I typed, which expanded into my stored name at once. I stared at the message in case there was a less explicit way of conveying the information, and then I sent the email.

Waiting a night and a day and its night as well before I could discover what Bella had wanted to learn felt like frustration rendered ponderously solid. By dawn I knew I couldn’t spend the day without involving myself somehow. Since I had no idea which site she and Roy planned to explore, I couldn’t risk visiting anywhere on Thelma’s list in case I encountered them. I thought of inspecting somewhere they’d already been – hadn’t Roy named a place? – and then I saw they were giving me the chance to carry out a different investigation. After a shower and an equally swift breakfast I made for my car.

In less than an hour I was leaving the motorway, and in a few minutes I was at the short cut Bella used. I parked outside a capacious Victorian house whose doorframe was buttoned with bellpushes next to handwritten tags. The deserted street was quiet except for the barking of a dog in an upstairs room. Fragments of brick clinked together as I stepped through the gap in the tottering wall.

The sharp shrill sound might have been displacing birdsong from the trees. A thin path elaborately patterned with dead leaves wound between them from the opening in the wall. Otherwise the trees grew so close together that it was impossible to see more than a few yards ahead. A solitary beer can lay just inside the wall, a token of an adventurer. I’d advanced several hundred yards through the greenish gloom when I caught sight of a house.