DI Wilson had already retrieved the old physical files from storage but, according to the boss, they were incomplete. So McCreadie’s notebooks might just prove to be by far the best source of information on the case.

It was from the first of them that McNab had pulled the family details, plus a list of suspects identified by McCreadie, which he had then forwarded to Ollie to check out. Handing over his current offering (or inducement) to Ollie of a large coffee and a Tunnock’s caramel wafer, McNab settled himself down to take a closer look at Ollie’s findings.

First up was their possible victim, with the photograph published at the time of her disappearance. McNab saw a wee girl, slim, with long dark curly hair and a wide smile. She was eating an ice cream, with a beach behind her, on one of the few days in Scotland when the sun had shone.

Her date of birth was 3 May, so she’d disappeared just two days short of her twelfth birthday. Ollie had also dug up a class photograph from her primary school. Those being the days of large classes, McNab had had to search for Mary among the many, eventually finding her in the middle of the second row from the front.

There wasn’t a photo of the dad or the mum, just dates of their deaths. Dave McIntyre had died almost ten years to the day after his daughter had vanished. Her mother, Evelyn, had followed two years later. There were no details as to how they’d died.

Two more photographs: one of Mary’s big brother, Robbie, who was fourteen when his wee sister went missing, and one of her sister, Jean, who was sixteen. You could see the family resemblance, despite Robbie’s scowl and Jean’s smile for the camera.

Ollie, tucking into his caramel wafer, was watching as McNab scrolled down through the details he’d unearthed in the short period of time he’d been given.

As McNab reached Robbie, Ollie added, ‘The brother has a criminal record. He went to Borstal for a spell, then prison for a short time. Both happened soon after Mary disappeared. Nothing on him since then. I’ve emailed you the details.’

‘And Jean?’ McNab said.

‘She married a Samuel Barclay two years after Mary went missing. As far as I’m aware, they’re still married and have two girls, now adults: Marianne and Lesley. Oh, and the good news is Jean and Sam Barclay’s current address is the family home in East Kilbride where Mary was brought up.’

So I have at least one survivor to talk to, McNab thought.

‘The best friend, Karen Marshall. Nothing on her?’ McNab said, realizing he’d reached the end of Ollie’s search results. After what McCreadie had told him about the pal, McNab was very keen to know of her whereabouts.

‘Sorry, I haven’t got anything on her yet,’ Ollie said apologetically.

‘What about Karen’s dad?’ McNab said. ‘McCreadie said he was a detective constable at the time. There must be something in the records about him?’