Turning off my alarm before it had a chance to ring, I slipped out of bed without making a sound. I brushed my teeth and went back into the bedroom, got down on my hands and knees and quickly pumped out twenty-five press-ups. Then I sipped the water by my bedside, looking out of the window at the October sky – six in the morning and still black over the nearby dome of St Paul’s Cathedral.

I got down and did twenty-five more push-ups, slower and more deliberate this time, thinking about technique. I gave myself a minute’s break then did twenty-five more, starting to feel it now, my arms shaking with the build-up of lactic acid in the muscles. I stayed on the ground, found my breath and forced out the final twenty-five – an act of will, not strength.

I padded quietly to the kitchen, anxious not to wake daughter or dog, but hearing Stan breathing in the dark, a snorting, snuffling sound coming out of a nose that did not really resemble anything up to the difficult task of breathing. I stood there listening to him, enjoying the sound. He was wiped out after another busy night of destroying our home. Then he stirred at my presence, the large ears falling across his face like silky curtains, the soulful eyes blinking open and glittering behind his lavish ears. And then he was awake too, staring at me through the bars of his cage, hopeful of an early release.

I got him out. Held him against my chest. Stan pressing a nose like a squashed prune against my fingers, sniffing them with interest.

Stan had been with us for a month (it felt much longer) – my present to Scout on her fifth birthday. I had found the breeder online, collected Stan on the day he turned eight weeks old, and carried him into the loft with a blanket over his head like a guilty man heading for the high court.

Every time I thought I had made a mistake, that the dog was my pitiful attempt to give Scout a proper family life, I remembered the first time she had seen Stan. Her smile was like the sun coming up. That’s how I knew the dog was not a mistake.

In the kitchen I drank a triple espresso with him on my lap, the only light coming from my laptop as I searched medical sites for information on how to cut a windpipe.

Stan went back to sleep as I learned that either side of the windpipe are carotid arteries, bringing blood from the heart to the brain, and that severing them is one of the most fatal head injuries known to man.

But no matter how many surgical websites I looked at, and no matter how many times I typed ‘cut throat’ into the search engine, I could find no weapon that looked remotely capable of doing the job.

In the end the search engine gave up on me, directing me to shaving websites where they sold foam, balm, gel and a variety of old-fashioned straight razors. They were interesting-looking blades, vicious enough to put a smile on Sweeney Todd’s face. But I couldn’t see how any of them could have cut deep enough to remove most of Hugo Buck’s throat.

At seven the sky finally started to lighten. I snapped shut the laptop as Scout appeared, padding into the kitchen still in her pyjamas and puffy with sleep.

Stan struggled down from my lap and flew at her. Our loft was huge. Far too big for a man, child and dog. Our family had grown smaller while the loft seemed to get bigger. Now we rattled around in all that empty space under the exposed wooden beams and brickwork, the dog’s paws skidding on the polished wooden floorboards as he chased towards Scout, sniffing and licking and nuzzling, clambering up her leg, crazy with love.