‘If you did it when he was halfway through a poem, I’d give you a prize.’

Well, she had done her utmost, she thought – though it seemed that her utmost had been, as ever, inadequate. And then she checked her stride, her whole body suddenly suffused with a glorious slackness, an unknotting that was almost spiritual (‘Burst Satan’s bonds, oh God of might!’) because the ordeal was over now. Other people might eulogize about love at first sight or joy in the morning but, personally, she didn’t know of any feeling more wonderful than that of sheer relief – the trap avoided, the snare broken. She’d got away with it again. Even though this time, of course, she hadn’t actually done anything wrong.

The cataclysm occurred three days later, on a viciously cold and sunny afternoon.

Noel had spent the morning at Dr Parry-Jones’s surgery in Finchley, dissecting the embalmed rat that she’d ordered for his birthday. It had actually been rather less interesting than he’d anticipated, but then the same applied to most of Dr Parry-Jones’s lessons. She taught him the sciences one fact at a time – cementing a straight and unvarying pathway, along which they progressed at a steady pace. There was thoroughness to her method, but no excitement or spontaneity; it made him ache for the way that Mattie had unfolded knowledge like a vivid map, showing him a dozen routes to every destination. Nevertheless, he found occasional, comfortable echoes of his godmother in the doctor’s presence: the large, blunt-nailed hands with their shiny knuckles, the coiled and plaited white hair, the knee-creaks, the deliberation it took to rise from a chair.

Noel and the rat had been placed in a small, windowless room – a makeshift pharmacy adjoining the consulting room, and containing a spirit stove, a pestle and mortar, a set of scales and a padlocked cupboard. While Dr Parry-Jones had been seeing patients, Noel had worked from the diagrams in a brittle-leafed textbook. He had measured the length of the gut (two feet, seven and a quarter inches from mouth to anus) and dissected the heart, flushing out the dark sludge to reveal the neatness of the four chambers. He had also sketched the lungs, weighed the liver and failed totally to find the spleen. The rat’s eyes had been partially open, its expression one of understandable disbelief.

Far more interesting than rodent viscera had been the odd snatches of speech seeping under the door. He’d tried not to be prurient – had actually stuffed his fingers in his ears a couple of times – but despite this, the hoarse weeping of one woman had cut through: ‘… he promised he’d be careful, he promised, he promised. Oh God, what will I ever tell my husband …?’ Dr Parry-Jones’s answer had not been audible.

‘Your initial cut has a distinct slant,’ she said afterwards, inspecting the hollow carcass. ‘I wonder if you suffer from astigmatism. When did you last see an optician?’