Catherine shrugs. “That’s what they said at the time. It started off feeling like I was just helping Mum out while she wasn’t well, but she never seemed to get any better and so I kind of took Alice over completely. Did everything for her. Every hour I wasn’t at school I was playing with her, feeding her, changing her nappies. It was almost as if…almost as if she were mine.”

She takes a sip of her cappuccino and I can see that there are tears in her eyes.

“She was a beautiful baby. I remember the way her tiny hands used to grip the bottle. And that blissed-out, drunk look on her face when she’d had her fill. Her milky burps when I rubbed her little back.”

I look away, my throat almost closing up. When I look back, Catherine is stirring another sugar into her cappuccino. There are tear tracks on her cheeks. The two of us sit in silence for a little while, each absorbed in our thoughts and memories.

“Sorry,” she says. “You were asking about your mum.”

“Please don’t apologize. I shouldn’t have started quizzing you. As you say, you were only a child. I’d be hard-pressed to remember much about my mum’s friends when I was that age.”

“But I do want to apologize about my behavior later on,” she says.

I look down at my lap. “It’s okay. You already have.”

“I know, but I want you to understand what it was like for me back then. After spending most of my childhood and teenage years looking after Mum and Alice and keeping everything ticking over while Dad was at work, I’d finally got a life of my own. Alice was about to start secondary school and Mum was almost back to her old self. I was going out to work as a secretary, enjoying a social life, making plans to leave home. Then you and Alice became friends and Mum got ill again. I’m not saying that was your fault, Lizzie, but in my head I associated the start of your friendship with Mum’s depression coming back. And then when Alice died…well, you can imagine…”

Her face lengthens in sorrow. I stare at my knees, the familiar undertow of guilt tugging my mind back to that fateful day.

“It’s why I was so mean to you,” she says.

My throat is too clogged with emotion to speak. To my shame, I’ve never once considered what it must have been like for Catherine, how much of her childhood and young adult years were eroded by the burden of caring for her mother and her sister.