McNab considered whether it was worth just spilling the beans. The body had been identified as Alec McLaughlin. In fact he’d been the one to confirm it himself.

She came in again. ‘He gave a story to the papers about Mary. About all of us. Said this was a street of evil back then.’ She looked distressed and angry about that.

McNab didn’t respond, judging it was his silence that was prompting Jean to talk.

‘He was a pervert back then and he went on doing that until they caught him. Think of all those children he got to in between.’

‘Was Mary one of them?’ McNab said quietly.

Jean looked shocked by the suggestion. ‘No. Definitely not. Robbie would never have allowed Alec near Mary. But Alec used to sit on the hill and shout things at her and Karen when they played tennis. Poor Karen, have you spoken to her?’ she added.

‘Karen Marshall has disappeared from her home in Stirling,’ McNab said.

‘Was this after our appeal?’ Jean said, concerned.

McNab nodded. ‘Karen didn’t approach us, but a friend in Stirling went looking for her after the TV appeal and found her missing from her home.’

A flurry of worry crossed her face. ‘Did we put her in danger?’

‘Why do you say that?’

‘All this time I prayed Mary was still alive. That someone had stolen her. Like women steal babies from the hospital. Like those snatched children in America who turn up years later. Maybe she’d just run away. Mary didn’t like getting belted, but at times she seemed to invite it. Always coming in ages after Dad had whistled for her. I nursed that notion all these years, until you found her in that bog.’

McNab had heard this before from Jean, but he was still moved by it.

‘Karen Marshall kept a diary at the time Mary disappeared,’ he said. ‘We haven’t seen it, but we believe it might throw some light on what happened that day.’

‘Is that why Karen’s missing? Oh God.’ She covered her mouth. ‘Is Mary’s killer still alive? Has he finally got Karen too?’

McNab didn’t want to register just how strongly that thought haunted him. He changed the subject.

‘The former DI McCreadie on the case, he remembered that Mary’s school clothes went missing around the time she did. He said a hand-knitted jumper, a grey skirt, white socks and sandals?’

Jean thought for a moment. ‘I remember our school clothes. Mum hand-knitted our jumpers, to match the school uniform. Mary’s was blue. Mine, being the secondary school, was maroon. But I don’t remember anyone saying they were missing.’ She looked at McNab. ‘Have you found these clothes? Is that why you’re here?’

‘We found what might be the jumper.’ He brought up the image Rhona had sent and passed the phone over.

Jean stared at it as though willing herself to recognize it.

‘It could be,’ she said finally. ‘Where did you find it?’

McNab wasn’t about to reveal that, not until Rhona checked it for Mary’s DNA. Instead he said, ‘If Karen comes here, it’s important you let us know immediately. You have my card?’