‘So this woman robbed Beatrice of her clothing?’ Karen asked.

‘She may have come across it by other means. It’s clean and undamaged, which we have to see as a good sign.’

‘There is one other thing,’ Karen said. ‘Beatrice knew how to look after herself. She was mugged once in Germany, years ago, and went on some kind of self-defence course, I don’t know what type. I know she sometimes carries a pepper spray.’

Gillard looked at the notes that the Met had provided. There was no mention of a spray having been found in her room. ‘That’s interesting,’ he said. Most types of pepper spray were illegal in the UK.

‘Is there any hope, detective?’ Ignacio asked.

Gillard shrugged. ‘If this was an abduction, yes. I think you can see this woman has gone to extraordinary lengths to create a fictitious journey for Beatrice. She had her phone, her precious violin and her clothes. Your friend would not voluntarily have parted with any of them, so the best hope we have is a kidnap.’

Gillard was back at Mount Browne by noon, and arranged an informal incident room meeting for one o’clock. In the meantime details had come by email via the Met Police about Beatrice’s bank accounts. For a supposedly struggling music student, Beatrice was not poor. There were several thousands spread over a current account, a savings account, and a separate euro account with a German bank. A solid monthly deposit was made into this from her parents’ account. But the balances were unchanged since Friday. Only the credit card had been used in the last four days, to buy a return rail ticket from Waterloo to Clandon on Sunday. That fitted with her journey to play at the wedding.

The biggest news was hiding at the end of the email. An asterisked section of the letter noted there had been an attempted withdrawal on Beatrice’s cash card on Tuesday afternoon at a cash machine in Earlsfield, where the impostor had got off the train. Gillard cross-checked the time and his jaw dropped. He double-checked the platform footage, and the last sight of the imposter leaving Earlsfield railway station. He swore softly to himself. It confirmed a growing suspicion, one that had been growing like a cancer in his gut ever since they had discovered the woman on the train was not Beatrice.

He gathered up his papers and walked into the incident room. It was nearly time. A whiteboard had been set vertically with marker pen notes to cover each aspect of the rail journey from Clandon to Earlsfield, with a parallel trace for the phone.

‘Okay, let’s get this meeting under way,’ he said. ‘I’ve got some fresh news for everybody.’

They all gathered together: DCs Hoskins and Macintosh, DI Claire Mulholland and DC Rob Townsend plus Christine McCafferty from the press office.