‘The investigation at the time found no trace of Mary after she had, we believe, taken part in her confirmation ceremony in the local chapel. The remains discovered south of Glasgow have now been identified as Mary. We appeal to anyone with any information on the case, however small, to get in touch with Police Scotland.’

The sister looked more nervous than the brother, and it was he who spoke first.

‘The original investigation was flawed,’ Robert McIntyre told the camera, ‘mainly because back then kids like us,’ he nodded at his sister, ‘weren’t listened to. In fact, when DI McCreadie, who was in charge, did take heed of what we were saying, he was hounded out of his job. This cannot happen a second time. Despite the intervening years, the memory of that day and what led up to it has never left me. And this time we will be heard.’ He paused for a moment to collect himself. ‘Anyone with knowledge about what happened back then, please come forward to the police. Mary’s killer could still be out there, and we want to find him and bring him to justice.’

The married sister, Jean Barclay, spoke next. She asked for the children who walked with Mary to the church that day to come forward. ‘Also,’ she said, ‘the police would like to trace Mary’s pal Karen Marshall. Mary and Karen were very close,’ she said. ‘Back then, Karen was in a state of shock when Mary disappeared and could hardly speak. She moved away with her family shortly afterwards and we lost contact with her. If she’s alive and listening to this, I urge her to make contact with the police. Maybe there’s something she remembers now about what happened on that day.’

Bill brought the session to an end with a final request for everyone who remembered anything regarding Mary’s disappearance to come forward.

The chatter in the room started up again as the picture snapped off.

‘That was being pre-recorded to go out later today,’ Janice said, ‘so the boss should be here shortly.’

At that moment Rhona spotted DI Wilson’s entry, along with McNab and Magnus.

‘That’s the criminal psychologist who lectures on the diploma course,’ McCreadie remarked. ‘To my recollection, he was given a hard time by the unbelievers in the audience, most of them serving officers.’

‘There was a time when forensic science got the same response,’ Rhona said. ‘It still does when something new is developed.’

McNab had spotted them. At first it looked as though he would head over, then he noted who they were standing next to and seemingly changed his mind.

Janice made an exasperated sound which expressed her thoughts perfectly. ‘Excuse me, folks, but I need to speak to my partner.’ She turned to McCreadie. ‘Just to say, your notebooks are making very interesting reading for both of us. So thank you.’

Deserting them, she threaded her way towards a disgruntled-looking McNab.

McCreadie smiled at her retreating figure. ‘I suspect DS McNab and I have much in common,’ he told Rhona.