‘The tricky Mr Johnny Lam,’ Claire said. ‘I don’t trust him.’

‘Indeed, he is one of the few people with a clear motive, seeing as Mrs Roy was always against selling the company. However if we go back to the evidence, the only people who would have been able to switch the contaminated deodorant for the one in Mrs Roy’s desk have been trusted family or close associates. Remember, this would have taken two trips, one to discover that Mrs Roy even kept a deodorant in her desk, and a second to switch the poisoned one in.’

Claire intervened again: ‘Unless, of course, Mrs Roy herself had brought in the contaminated deodorant from her own bathroom or from her flat in Leatherhead.’

‘Yes, there is that possibility. Sadly but predictably the only DNA or fingerprints on the deodorant are Mrs Roy’s. We’re unlikely to ever get to the bottom of how the deodorant found its way into her desk. All that we can say with certainty is that those with the easiest access would be, in order: her PA Philippa Boswell, Morag Fairburn and Harry Roy. Then there are the two sisters, Prisha and Kiara who, though not frequent visitors, would tend not to be questioned. There is also Deepak Tripathi, possibly Simon Parr-Fielding, Prisha’s partner, and the office contract cleaner. We should also consider the wedding planner, any senior employees, and so on.’ He wrote down the last few names, which had not yet been added to the whiteboard. He then turned back to the meeting.

‘I think you can see that we have real difficulties here. Those with the easiest access to her have the weakest motive. We’ve picked up plenty of DNA from employees and family members around Mrs Roy’s office, but not on or in the drawer where she kept the deodorant. Frankly I don’t think this case is going to be solved by forensics. While it seems clear to me that many in the family have various grievances, some of them quite understandable, there is no proof of anything. That is why I would like to turn to the third strand of evidence.’ He stepped across to the third whiteboard, on which all the details of the crime scene and the Toyota Avensis were recorded.

‘This is where I would like to put the most effort. Now while we only have the witness report of Ms Mockett to put the Toyota near the scene of the crime on that Sunday morning, we certainly do know that a vehicle belonging to Morag Fairburn passed through a number of ANPR cameras within ten miles of Ashtead Common, and finally we have managed to get some CCTV images of the driver.’ He taped up on the whiteboard the best still image they had from the filling station, which showed a side view of the man. ‘This, in my view, is our best lead on the man who killed Mrs Roy.’

‘He’s trying to disguise himself,’ Carl Hoskins said. ‘The hat pulled low, the sunglasses and the beard.’