There were far fewer resources where the fake Beatrice’s journey began. There were no CCTV cameras on the roads approaching Clandon station. The first glimpse of her approaching in the rain on the Tuesday afternoon was in the station car park. Gillard described to the assembled detectives how he and Claire Mulholland had driven all round the village of Westmeare, the last place that the real Beatrice Ulbricht was seen. They had visited plenty of quiet lanes and sunken rural drives where a body might easily be abandoned, while uniformed officers had leafleted and knocked on doors around the village. There were no obvious fresh leads.

‘What about the London angle?’ Hoskins asked.

Claire, who had been coordinating with the Metropolitan Police, answered that. ‘None of Beatrice’s fellow musicians are in the frame on this. We don’t believe that the answer to this crime will be found within her musical community.’

‘What about Adrian Singer?’ Rainy asked. ‘He’s a wee bit creepy.’

Gillard shook his head. ‘He may be the best suspect we’ve got, but he came out clean, forensically. There was no trace of Beatrice’s DNA upstairs in his home, only on one dining chair and one seat cushion from the sofa, which matches his story that she came round for dinner and then left. His car showed some of her DNA on the passenger seat, but nothing in the rear seats or boot.’

‘So do we really believe that she was just randomly snatched from a bus stop?’ Rainy asked. ‘It doesn’t quite fit with all this elaborate cover-up and the impostor. That speaks of weeks of planning, surely, yet it happened within two days of her disappearance.’

Gillard nodded. ‘That’s an excellent point. I think the word to discard here is “randomly”. It just doesn’t fit. There has to be a reason.’

At two p.m. DCI Gillard Skyped Dr David Delahaye at Redhill Hospital, before he performed the post-mortem. The forensic pathology consultant appeared to be sitting in a small windowless office. Leaning forward into the fisheye lens his square spectacles and balding dome made him look like he belonged in a flying saucer. The right-hand side of the computer screen was dedicated to the photographs that they were sharing.

‘This is the dead girl,’ Delahaye said, as a close-up image of her face flashed up. Alabaster skin, bluish lips, eyes closed, dark blonde hair. But the overwhelming impression was of innocence; pure, fresh, and preserved for ever. The pathologist flicked through a series of images taken on arrival at the mortuary. They were mostly of her face. The last few were full body. Her clothing was intact, a woollen cardigan over what looked to be a white blouse, a pleated skirt, fawn tights and no shoes.

‘No make-up,’ Gillard said.

‘Unpierced ears, no nail varnish,’ Delahaye added. ‘She may be even younger than she appears. She is the typical height of a thirteen-year-old. Forensically speaking, what we are missing, if she drowned recently, is foam. It would be normal to find froth in the mouth, and upper airways. I will perhaps be in a better position to assess this once I’ve opened her up. Froth in the smaller airways, oedema, even overinflation would give us a better guide.’ He looked up at the detective. ‘However, as you may know, determination of drowning is one of the trickiest areas in all pathology. Immersion in water can kill in many ways, not just by filling the lungs with water. Hypothermia, stress, hypertension and cardiac arrest can all kill, particularly someone who may be trapped in a partially submerged vehicle.’