Peter sits down at the breakfast bar now and fills his bowl with plain yoghurt and granola. He reaches for the last banana in the fruit bowl to slice on top. His sister doesn’t like bananas, but now that Peter’s taken the last one, she wants it. She snatches his bowl away, and he sighs, but doesn’t object.

‘Give that back,’ Tom says.

Our daughter regards him, flat-eyed, and spoons a mouthful of granola and yoghurt between her lips.

‘Give the bowl back to your brother,’ I say.

Medusa shrugs and sends it skittering across the counter towards him. ‘I don’t want it, anyway. The granola’s got mouse droppings in it.’

Peter yelps and shoves the bowl back. ‘Ewww!’

‘Enough,’ I say, in a tone of voice that silences the pair of them. ‘I need to shower and change for work. You’d both better be ready to go when I come back downstairs. Your father doesn’t have time to take you to school today, so I’m dropping you off.’

This is a rare event. Part of our deal when we decided to have a child was that Tom would assume the lion’s share of hands-on parenting. We both knew that however good my intentions I’d quickly lose interest in the repetitive routines of childcare, perhaps with disastrous consequences.

I was quite clear when Tom asked me to marry him: I had no desire to replicate myself, no romantic longing to blend our genes. Frankly, given my childhood, I was a rotten proposition as a wife all round, but Tom was touchingly undeterred.

Perhaps it’s because we grew up together. He was, quite literally, the boy-next-door. Our parents owned adjoining semis on Kennedy Road, a cul-de-sac in what an estate agent would no doubt call a ‘leafy’ part of West Sussex. My parents bought Number 17 when my mother was newly pregnant with me. Three months later, Tom’s parents moved into Number 19.

My mother wasn’t sick then. There are photographs of her and Tom’s mother showing off their baby bumps together in the back garden. In some of them, my mother’s even smiling.

We were born two weeks apart in June 1982, just as the Falklands War was coming to an end. We went to the same nursery school and we were inseparable. Even when we moved up to primary school, and Tom made friends with other boys, he stayed loyal to me.

I spent more time in his house than mine; his mother, Amy, showed me more love and care than my own indifferent, sometimes hysterical, mother ever did. Amy fed me when my parents neglected to, and gave me a lift home from school when my father was drunk and my mother had taken to her bed with ‘nerves’.