Esson rewound the footage. Haggard could have relied on his various debit and credit cards, but he was old-school. He’d paid cash at the tiki bar and cash to the driver who’d taken him to Till’s. She would bet he’d been the type to press tens and twenties into the hands of nightclub staff and maître d’s, probably never ordering a drink, as he had done at Drifter’s, without adding the words ‘and one for yourself’. When the cash had appeared from the slot in the machine, he’d counted the notes a couple of times – either to check he wasn’t being short-changed or because his arithmetic had been blurred by drink – before pocketing them, adding the balance slip that had popped out at the same time. A member of the casino’s floor staff had been hovering at a discreet distance, but had then approached to suggest it was time for Haggard to call it a day. Haggard had held up a digit – wanting one more drink – and the employee had eventually relented, leading him to a table and indicating for a waiter to take the order.

And yes, he had tried tipping the man, but it had been refused.

‘Did you talk to this guy?’ Esson called across to Leighton and Gamble. ‘The one who let Haggard have a last drink?’

Leighton nodded.

‘Did he say why he turned the tip down?’

‘He only takes gratuities from the sober.’

‘Why?’

‘Because drunks don’t know they’re doing it, which makes it meaningless.’ Leighton nodded again at Esson’s raised eyebrow. ‘The guy’s a philosophy graduate,’ she explained.

‘For real?’

‘For real,’ she confirmed.

Esson gave Clarke a look before returning to the footage. A switch of cameras now, Haggard at his table, shot from further away, the resolution less clear. Then an approach by two members of staff who were an altogether more imposing presence than the philosopher. They watched Haggard drain his drink and then helped him to his feet. He didn’t put up any resistance and they didn’t have to use force. Cut to the front entrance, and the taxi was already waiting there. The same two men manoeuvred Haggard inside and closed the door. The taxi didn’t leave immediately, though. The door opened again, Haggard’s hand emerging. One of the men who’d led him from the casino took the banknote held out to him, folding it into his pocket. No philosopher he. His companion seemed to be angling for his share as they made their way back indoors and the taxi pulled away.