Hoskins muttered: ‘Unless he came out all furious from home after the row, found her at the bus stop and clouted her one.’

‘We’ll check all that out when we re-interview him,’ Gillard said. He then detailed the fact that Beatrice’s bank accounts had not been touched.

‘I have got one very clear and significant piece of evidence that has come to light in the last hour,’ he said. ‘The banking audit trail shows an attempted cash withdrawal from her current account at a Spar supermarket in Earlsfield on Tuesday afternoon. Two attempts were made on the pin code, neither successful. Obviously not a third attempt because failure would have blocked the card.’

‘So maybe it is a robbery,’ Rainy said.

‘I’m thinking that it’s actually an attempt to communicate with us,’ Gillard said.

Everyone looked confused.

‘I don’t get it, sir,’ Hoskins said. ‘What is she trying to tell us?’

Gillard smiled. ‘The attempted withdrawal took place at 4.35 p.m. on Tuesday. At that time our impostor had not yet arrived at Earlsfield. She didn’t arrive until 4.37 p.m., according to platform CCTV.’

‘Jesus, sir, this is doing my nut in,’ Hoskins said, holding the shaven-headed article for emphasis. ‘How did she manage that?’

‘She’s a witch, told yers,’ Rainy said. ‘First she manages to be invisible, then two places at once, now time-shifting.’

The detective chief inspector shook his head. ‘Without seeming to be too misogynistic about it, I’d like to suggest that our impostor is simply a clever distraction. The purpose of the attempted cash withdrawal was simply to demonstrate to us that a second person is involved. This person, let’s assume a male, has a significant job to do. He drops the Beatrice double off at Clandon for her train journey, then drives up to London to pick her up again at Earlsfield, while the phone she abandons in the bin makes its merry way onwards to Brentford.’

‘Wow,’ Townsend muttered to Christine. ‘All stitched together so it makes sense.’

‘Any CCTV at the cash machine?’ Claire asked.

‘Surprise, surprise, no. It’s one of the few in the area without a camera,’ Gillard said. ‘I’ve already asked the Met Police to forward any street CCTV to us, but I’m not holding out my hopes. I think this particular location was picked very precisely, by someone who knows how to plan.’

‘What’s the next stage?’ Townsend asked.

‘ANPR. I want the nearest number plate recognition cameras to Earlsfield around that time matched to any we can drag up from around Clandon or Westmeare an hour earlier. There’s a fighting chance we’ll get a match. I also want to drag in Adrian Singer and turn the screws a bit. I’ve already obtained the search warrant. Any questions?’

‘So definitely no ransom demand here or in Germany?’ Hoskins asked.

‘Nope. Not a thing. In six days there should have been something. I’m particularly concerned because of the twice failed bank card transaction.’

There was a short pause while the implications of that sank in to the assembled detectives.