He brought the lights back up, then walked over to the whiteboard on which the train’s movements were detailed from top to bottom. ‘This is the fact that I want everybody to concentrate on. At some point on this fairly busy commuter journey, Ms Ulbricht and her phone parted company. Now it’s conceivable that she left her phone behind, and that somebody else may have dropped it in a bin. There aren’t really any other obvious reasons why her phone would have found its way into a rubbish container.’

Rob Townsend had raised his hand. ‘Sir, just had the phone contents relayed to us by the service provider. The last text message Ms Ulbricht sent was at 16.39.’ He looked down at his phone. ‘The message was: “On the train now. Just arriving at Clapham Junction”.’

‘Okay Rob, so she was nearly into central London. I want to know who that message was sent to, and the thread of any conversation,’ Gillard said. ‘Cross check the time with when the service really did pass Clapham. That could well be the breakthrough we’re looking for.’

He turned to the others. ‘All right, CCTV people, I want you to concentrate on any platform footage from Clapham Junction and Vauxhall, and leave Waterloo to British Transport Police. Discarding the first dozen stations should save us all some time.’

‘What are we saying to the press?’ Claire asked.

‘The indication so far is that we’re talking about a missing person. We are worried for her safety, because it would not be normal for her to miss an important concert engagement, but at this stage we don’t have an indication that anyone else is involved.’

‘Have we got any good pictures of her wearing the hat?’ This question was from press officer Christine McCafferty. ‘I think it would help to have good pictures of her, with what she was actually wearing, rather than this glamorous publicity pic with evening dress and her hair—’

Claire interrupted. ‘Before we get to the point of considering her safe, you should know that our Mr Singer, who had offered to put Ms Ulbricht up for the night, was interviewed by Sussex police in 2007 over an incident at the private school where he was head of music. He left the job shortly afterwards.’

‘Was he ever cautioned?’

‘No. There were allegations but no evidence, a least no evidence the school was willing to put forward. But after eleven years there he left within a week.’

‘Okay,’ Gillard said. ‘That’s useful information. But we must stick to the evidence. She seems to have been alive and kicking long after leaving his clutches on Sunday.’

At this point the chief constable stood up, the full six foot two, and made her way to the front. ‘Thank you for this, Craig, you sound like you are fully on top of it. While it would obviously be a huge relief if Beatrice Ulbricht is found unharmed, I think we should make sure we are not missing any avenues here. If you need more resources, just let me know.’