‘He’s still in bad shape, sir,’ said Charlie. ‘Ruth Bussey’s explained it in Seed’s presence. I was there. I saw him confirm her explanation as best he could. Seed regretted having told Bussey he’d killed Trelease. He got cold feet about facing up to the truth after all these years, and by that time he knew Martha Wyers was calling herself Mary Trelease, so he decided to turn what he’d originally intended to be the beginning of his true confession—“I killed Mary Trelease”—into an easily disprovable false one.’ Charlie shrugged. ‘I know you don’t like it, but it does make sense, sir.’

‘If that’s your opinion, Sergeant Zailer, then you have my condolences.’

‘We’ve been through this,’ said Simon impatiently.

‘Not everyone’s mind works in exactly the same way yours does, sir.’

Proust gave Charlie the look he reserved for despicable traitors.

‘Even if we accept Bussey and Seed’s explanation and a revised confession from Seed, it’s going to be an uphill struggle if Len Smith sticks to his story,’ said Sam Kombothekra.

‘The CPS don’t do uphill struggles, sergeant. You know that as well as I do. They prefer gentle strolls down country lanes.’

Sam nodded unhappily. ‘In their eyes, Smith’s a killer, yes, but he’s not a liar.’

‘He isn’t a killer,’ said Simon. He wasn’t interested in other people’s eyes and the things they saw that weren’t there. After last week he was less interested than he’d been before. Most people were idiots, even those whose rank and years of experience might suggest otherwise. Coral Milward had been so determined to nail Stephen Elton for Gemma Crowther’s murder that she’d wasted God knows how much time trying to break down what she’d called Elton’s ‘suspiciously solid’ alibi. It was solid because he’d been telling the truth.

Elton, Simon had heard from Colin Sellers, was a habitual user of prostitutes, both male and female. (‘No droughts for him, lucky sod. World’s his oyster—both hemispheres.’) After helping to clear up at Friends House on the night Gemma was murdered, he’d paid a visit to one of his regulars, a sixteen-year-old called Sharda who shared a bedsit in Seven Sisters with three other illegal immigrant sex workers. Elton’s alibi was also his motive: Gemma Crowther had known about his habit and regularly threatened to expose it to their Quaker friends if he didn’t follow her orders to the letter. Effectively, he was her domestic slave. Elton had been foolish enough to admit to Milward that he’d frequently fantasised about killing Gemma, and only didn’t because he loved her. ‘You’ve got to admit, though, that’s a good reason,’ Sellers had remarked this morning to Simon, entirely without irony.