‘That would be a great start, Rob. We’ve got one additional line of enquiry,’ Gillard said. ‘Attached to the documentation of the e-ticket he bought is the booking of a hire car through Avis at Heathrow. Rainy, I’d like you to follow that up and see whether the car was ever returned.’

‘Okay boss.’

‘The Taipei police have been incredibly thorough already,’ Gillard said. ‘They have given us an entire data dump from the phone service provider for his work and personal phones. That includes all the messaging by text or email, although not WhatsApp. Most of what we have now is in Chinese, but they have offered to translate it into English.’

‘Top marks,’ said Hoskins. ‘That’s above and beyond.’

‘I get the impression that considering the prominence of the man, they want to get a fairly rapid result,’ Gillard said. ‘I told them we did too.’

Gillard was waiting for Rainy Macintosh to get off the phone to Avis car rentals when Research Intelligence Officer Rob Townsend beckoned him over to his computer, on which was displayed a high-resolution map showing a faltering yellow trace heading west from Heathrow airport. ‘This is the journey of Dr Chen’s phone on the morning of June seventeenth,’ he said. ‘The mobile was on presumably from the moment he arrived. He headed down behind Heathrow, through Hounslow and Feltham. He certainly looks like he was heading for our patch. But then the signal stops, and never goes on again.’

‘I’m pretty sure that’s not the way that the satnav would take you if you’re heading to Oxford,’ Gillard said. ‘And I’m guessing, but I don’t think he would have known the backroads and rat runs in that area.’

Before Townsend could give his own response Rainy called over, having just finished her call. ‘He booked the hire car, but cancelled on the day by phone,’ she said.

Gillard and Townsend stared at each other. ‘So maybe someone gave him a lift?’ Townsend said.

‘Seems the most likely. With luck, we’ll know when we get the contents of his phone.’

‘How long do we have to wait for the translation?’ Rainy asked.

‘They promised us a day,’ Gillard said. ‘But you know, if he was messaging somebody about a lift from Heathrow, it would probably be in English, wouldn’t it?’

The three of them crowded around Gillard’s screen while he downloaded a PDF from the Taipei police email. Most of the messages were in Chinese script, but as the data was sorted by date and time, he was able to home in on a message sent soon after the Taiwanese man landed at Heathrow.

Dear Mr Chen, the driver will be in arrivals with a card with your name on it.

Looking forward to seeing you.

Penelope