‘That’s the window.’ Arm-in-arm, she halts us before the basement. An office block conversion, well-built in what I suspect is genuine Georgian sandstone – certainly beyond the fiscal or physical reach of my impoverished east end ancestors – but otherwise unremarkable. Undramatic. Unless one knows the truth. ‘That’s where she passed him the poison. They say she put it in his hot chocolate.’ Elbows linked, Maddy’s eager gesture with her takeaway cup causes mine to spill.

‘Clever,’ I observe, a little preoccupied with wiping rogue droplets off my sleeve and, when that strategy fails, surrendering to massage them into the leather (regrettably, my better jacket, given our destination). Glancing up from fingertips fast-stained cocoa, it strikes me that this is an oddly anodyne spot for murder. Even a middle-class one. Although I admit that the iron railings add atmosphere. Maddy crouches, dragging me down with her to peer through those twisted, teardrop-finial black bars, staring as if with sufficient intensity she may see through time too.

‘He had it coming.’ She murmurs the words, mouth less than an inch from the wall as if confiding her secrets to stone. Not the first these bricks have heard. ‘He shamed her. Humiliated her. Threatened to blackmail and destroy her. She didn’t do it. But he had it coming, all the same.’ Gaze trained on the pane despite the blinds beyond pulled tight, presumably to prevent prying eyes like ours, she takes a sip to steady herself. A crest of foam clings to her chocolate-dipped top lip. ...