A further pause beset by static. ‘Dedic, Novak is moving. The Shard, London Bridge Station. See you there.’ The voices faded and were replaced by the tinny sounds of the television.

Tom stood and looked out of the window, down to the junction with City Road. After about three minutes, a dark Range Rover Evoque appeared and turned right onto City Road at speed. Tom could see Zjelko’s buzz-cut hair at the driver’s seat. He noted the registration number of the vehicle and then sat down to wait for Pet to return.

*

Pet returned forty minutes later with a soft triple knock at the door and a smile on her flushed features.

‘All go okay?’ she asked, walking back round to her laptop.

‘They got the call minutes after you switched on and dashed out to go to London Bridge. We now need to know the number who called them: that’s our bent cop.’

‘Back to work, Detective. Let’s see what we can find,’ she said as she began attacking the keys with renewed gusto, concentration etched on her face. ‘Okay. Zjelko on 219 was called by a number ending 109 just after I used your phone. Zjelko then called a new one ending 659 immediately after that,’ she said.

‘That would be Dedic; he despatched him to London Bridge after the call. We need cell sites and call history on 109. Can you also do open source and anything else you can think of on that number in case the bent cop has used it elsewhere, assuming it’s a dirty phone?’

‘I’m on it,’ said Pet, tapping away at the keys.

Finally, we’re making progress, thought Tom. They had the number for the dirty cop, and so they were one step closer to identifying him and blowing the whole thing wide open. None of what they were doing was evidential, nothing could be used in court: the bug was unauthorised and the phone data hacks that Pet was doing could never be admitted to either. Tom was effectively riding roughshod over the law. He just wanted to get to the bottom of it; he could figure out how to make it evidential later.

‘Okay. 109 is an unregistered pre-pay with no details attached to it at all. A typical burner phone. It receives a call from 079—which was your NCA man—just after I disabled airplane on your phone. That must be to your primary bent cop who is receiving information on the intercepted calls from the NCA agent. He’s made and received several calls recently to Zjelko and the 079 number; he also made other calls to other numbers a little while ago which I can look at,’ she said. ‘I’m running 109 through an open source software package which will find any time it’s been entered into the Internet.’

Tom said nothing, impressed with her skill.