‘What about Harold Garrison, the uncle?’

‘I interviewed him a few times. He was gutted, as befits a fishmonger. Very fond of Jane he was. Frank and Eileen only had the one child, and to lose her like this. Well.’ He shook his head.

‘Was it just a stall he ran at the market?’

‘No, a proper shop. Shellfish, mainly. The old days of jellied eels, cockles, whelks. The old London food. Of course these days, it’s all ciabatta, gnocchi and fucking avocado. The Hildreth Street market has been gentrified to death. Most of the old stallholders and shopkeepers have long gone. Even the halal butchers. The only one I recognise these days is the West Indian hairdresser’s which has been there decades.’

‘Did you ever visit his fish shop? Did it have a big deep-freeze?’

‘Don’t remember. I suppose he must’ve had one, in his line of business. He closed the shop a year or two after her death, and moved away.’

‘Still in the fish business, was he?’

‘No idea. I was moved on to other cases by then.’

Perry had been keeping his trump card for the end of the interview. ‘I can tell you now, that we found Jane’s body floating in a river in Surrey just a few days ago.’

‘You’re kidding me.’ His jaw hung open, revealing tiny white flecks of saliva at the corners of his mouth.

‘I’ve got some photographs,’ Perry said, getting his iPad out.

‘Go on then,’ Mottram said, switching his specs to a half-moon pair. ‘I don’t imagine I’d recognise her after all this time.’

‘I think you will,’ Perry said. He flashed up the image that had been taken in the mortuary, while she was still wearing the skirt and cardigan she had worn on the day she disappeared.

‘Nah, that must be an old photo,’ Mottram said. ‘It’s exactly the same apart from her hair.’

‘That photograph was taken four days ago. The post-mortem showed she has spent the last thirty-seven years frozen solid.’

Mottram blinked, and removed his spectacles to wipe his eyes. ‘Oh Jesus, it’s like time has stood still.’

Perry looked at this big powerful man, and then a few thoughts dropped like coins into his mind: Mottram is the right age to have killed Jane Morris, and even today could still have overpowered Beatrice Ulbricht too. Maybe a bit too unfit to have chased Gillard up a hillside, but the combination of police experience and electronics expertise might give him the forensic nous that their killer had shown. The hairs on the back of the detective’s neck stood up. He didn’t like Mottram, and he didn’t trust him.

Friday afternoon saw DI Perry sitting in the cavernous and poorly lit basement of Tooting Police Station in South London. He was looking up the original interview notes from 1982 with Jane Morris’ uncle Harold Garrison, and much else besides. There was a huge archive of historic police records kept down there, culled from the various local police stations which over the years had gradually closed. Much of it had been put on microfiche, the favourite archiving system of the immediately pre-computer era, but one that had now been superseded. The librarian had shown Perry how to manoeuvre the lens over the dark blue sheets of microfiche on the light box’s glass plate to get the correct part underneath the magnifying glass, which then projected it onto the large screen, which was very much like a computer monitor. After a few minutes he got the hang of it, and was able to whizz from one sheet of evidence to another. The construction of a misdirected investigation was quite easy to uncover from this perspective.