‘Pity we can’t put Seed brother and sister behind bars,’ Proust muttered. ‘For presenting themselves as victims of equal status as much as anything else. By the time Mary Trelease appeared on the scene, they were both about to leave home. They couldn’t have gone to the police once they’d left? No, not them—they opted to drop in for tea and cake every so often instead, witness one or two horrors, then be on their way.’

‘I think the tea and cake would have been more like cheap cider and smack, sir,’ said Charlie.

‘We’re getting sidetracked,’ said Simon. ‘Of course Smith isn’t going to tell the truth: that he ruined his stepson’s life, then brought in a woman who’d already been judged unfit to be around children to ruin it a bit more. Smith might have loved Seed—he might have needed him as a comfort blanket—but that need placed Seed directly in the path of Mary Trelease, and he knows it. Night after night, she’d wait until Smith was out of it and force herself on Seed. Eventually, he got so desperate that he closed his hands around her throat and put a stop to it once and for all, for which I don’t at all blame him, and what was Smith doing when that happened? Sleeping off a bottle of whisky at the far edge of the mattress, drooling onto his sweat-soaked pillow? Do you think anyone’d want to tell that story about themselves? Smith’s going to cling on to his lie for dear life, whatever he thinks Seed might or might not want him to do.’

‘Which is why we find ourselves in a predicament,’ said Proust, righting his empty mug. He knew exactly how pleased everyone was that the knocking noise had stopped; Simon could see it on his face. ‘Thank you, Waterhouse, for defining things so clearly. Len Smith will cling to his story. Aidan Seed, as soon as he’s strong enough to do any clinging, will doubtless cling to his, and the CPS will cling with equal ardour to their right to finish work on the dot of three o’clock, after which time they get a nosebleed if they remain at their desks, as we all know.’

‘Have you told him about the painting?’ Charlie asked Sam.

‘I wouldn’t rely on Sergeant Kombothekra to transmit information if I were you. Considerable time and energy could have been saved if his initial searches, which he assured me were exhaustive, though perhaps he meant exhausting, had brought to light a twenty-six-year-old murder.’

‘I was looking in unsolveds, sir,’ said Kombothekra. ‘There’s no database of victims’ names. How was I supposed to . . .?’

‘What’s this about a painting?’ Proust asked Charlie.

Simon swallowed a sigh. Hopeless; why was she even bothering?

‘I don’t know it exists, sir, but if it does, it might help to clarify things.’