‘Let’s start with the evidence. Beatrice Ulbricht was last seen on Sunday leaving a wedding reception in Clandon, Surrey. That was five days ago, and is the last cast-iron evidence of her movements. She was given a lift by a friend called Adrian Singer and, according to him, intended to return to the station by bus from the stop near his house. There is no bus at that time. From eleven p.m. on Sunday to three p.m. on Tuesday she disappears, phone off.’ He tapped the whiteboard. ‘Then we have two ghosts, both elaborately conceived in an attempt to deflect the search for her. One, we have the movement of her phone from the time it was turned on at around three p.m. on Tuesday, via a journey by train up to Waterloo, being consigned to a waste receptacle on the train at some stage, before turning up at the Brentford waste transfer station. Pre-prepared texts were set on this phone to be sent at various points along the journey. That is ghost number one. The second phantom, and an equally impressive feat of organisation, is a young woman, taking the same train as the phone, wearing Beatrice’s distinctive fedora, overcoat and scarf, and carrying her violin. This young woman was very careful to hide her face from CCTV. We know nothing whatever about this impostor, but will be focusing more on her later.’

He turned back to a whiteboard on which was pinned an Ordnance Survey map of the area around Clandon. ‘What I want to do, belatedly, is focus the inquiry closely around the area from Clandon to Westmeare. Someone has been working very hard to distract us from this location, but I think it is crucial to our inquiry.’

Christine put up her hand. ‘I’m having to deal with a lot of pet theories from members of the press, sir. The Sunday Times insight team is working on some big piece, and I’ve had numerous calls from the German dailies which have asked us to comment on various political or kidnapping ideas. I’ve just had to say “no comment.” Is there anything you can tell me?’

‘Not at this stage, Christine. We are still treating her as a missing person, although I think many of you know that I’m increasingly worried about her safety. I am hoping it is an abduction, because the alternative is worse.’

Carl Hoskins interrupted. ‘Are you thinking she was kidnapped by that other woman, sir, the bird on the train?’

Gillard smiled at the detective constable’s slang, though he was aware it grated on many nerves within the department. ‘No, Carl, I have another theory, and in a few minutes I shall show you the proof. First let’s deal with the eyewitnesses to the impostor.’

He handed over to Claire, who ran through a fat clipboard full of summarised statements from those who had rung the helpline or sent in emails. ‘Sadly, we have no one who saw our impostor arrive at Clandon, and only a couple who noted her departure from Earlsfield railway station,’ she said. ‘We do have one witness, in a vehicle, who claims to have seen Beatrice at the bus stop in Westmeare at around eleven on Sunday night. I want to emphasise that we think this may be the real Beatrice Ulbricht. If so, it might mean that Adrian Singer is in the clear.’