‘Yeah, let’s – later,’ said Simon, whose tolerance for Moore’s isn’t-it-all-jolly tone was fast evaporating. ‘I’m in the middle of recapping Angela McCabe. Like Linzi and Rhian before her, Angela also found a small white home-made-looking book, stapled in the middle, with no more than one word on each page. Together, the words added up to a line from a poem by Ella Wheeler Wilcox, an American poet: “Somebody’s baby was buried to-day”. Angela found the book in her handbag. Her husband said it was her favourite bag; she always had it with her. Anyone could have followed her and slipped it in at some point. After dropping her kids off at school, Angela was in the habit of going for a coffee at the Whole Foods Centre on Magnier Road in—’

‘Whole Foods Centre!’ Proust pounced on it. ‘And we’re expected to believe she’s not a hippy.’

‘The point is, it would have been easy for Billy to learn that Angela could be found there most mornings,’ said Simon. ‘At the Whole Foods Centre. Easy for him to be there too one day and slip the booklet into her bag.’

‘Also worth mentioning that Angela got a line from the same poem that Josh Norbury did, in his little white book,’ said Grace Woolston.

‘Norbury’s line was “And a shadow seemed drawn o’er the sun’s golden track”,’ said Sam.

‘Yes, this is crucial,’ said Kerensa Moore. ‘Sorry, DC Waterhouse – I know you’re keen to go on, but we need to state at every opportunity: this is Billy’s way of telling us that it’s about pairs of best friends, in case we were too slow to work it out. Rhian and Linzi got lines from the same poem. So did Angela and Joshua.’

‘The pairs thing was frustrating in the case of Angela,’ Simon went on. ‘The unmissable link to Linzi and Rhian via the little white book, I mean – because if that hadn’t been there, telling us it had to be the same killer, there’d have been an obvious suspect for Angela’s murder: thirty-six-year-old Gisela Bloor, receptionist at a car showroom in Ealing. Bloor has been semi-stalking Angela’s husband Russell for years, making a nuisance of herself in the guise of being a dedicated kung fu student. Russell McCabe wasn’t interested in her and nothing ever happened between them, but Gisela told everybody, including Angela and Russell, that she and Russell were destined to be together. It’s what the universe wants, apparently, she told anyone who would listen – and it would happen eventually whether Russell accepted his predetermined fate or not.’

‘Another unhinged hippy,’ said Proust.