We took the same seats we had the previous time: the two priority seats, next to the wheelchair space in the bus, him on the aisle, me and C by the window. There was an order of service rolled in his palm, but I knew where he’d been anyway. Knew the route took him to his church, knew his church was near the station, knew we both rode the same bus to get there.

I suppose he’s in his Eighties; lost his wife a couple of years ago. I don’t know his name but I recognise the voice, the tufts of white hair, the way he leans in because the hearing aid isn’t doing its job right. We’ve taken the bus a few times now and we always talk for the journey. I don’t think he remembers me, but he’s always the one to strike up conversation. Asks if C’s name is Irish, and when I tell him it’s Shakespearean he asks if I’m an actress. We talk about theatre, we talk about the music at his church, we talk about the neighbours who have become his ersatz grandchildren, we talk about the baby.

Its one of my favourite bus chats, which I have been quietly collecting for a while now. Londoners, famously, don’t talk on public transport. But I think this is a Tube thing, or maybe a rush hour thing or a baby thing. I exist in a different plane of the city now, one made of buggies and carers and more vulnerable people, whose days don’t take place in offices or after hours. We ride the buses, we squeeze into the bit for wheelchairs and prams, we sit alongside the wheeled shoppers and suitcases, we sing to our fractious babies and let them starfish their hands at the steamed-up windows. We talk to one another.

It started when he was tiny and I was desperate to prove to myself I wouldn’t be hemmed in. The first nice day in weeks and I wanted to see the blossom, so we went to West London - somewhere that always feels like another country to me - and walked through Kensington Gardens to a book shop in Holland Park. In hindsight it was lunacy, even walking was painful, but those newborn days had been airless at times. We ate hummus with warm bread on the pavement outside a Lebanese cafe and it felt like a holiday.

But back to the bus, when it started. An American couple in their seventies peered into the pram. The baby was so small you couldn’t really see him in there, all bundled up. “How old?” they asked.

Eight months have passed and I still get asked it. It’s a rare constant in a phase of life that seems outwardly the same but changes daily. I have answered 16 days, four weeks, eight; three months, five, six, eight. We talk about his eyes, his sleep, his hair, his runny nose, his smile. We talk about their babies, their grandchildren, their memories.

I like the bus chats. Nobody told me to expect them. I remember when C was six weeks old and a woman with an older baby was particularly talkative; she opened up on the stretch of road between Vauxhall and Stockwell, told me about how she lost her sense of self, how she found it really hard, how CBT helped, actually. I found it a bit much at the time. Now I realise she was just being kind, an all-too-rare instance of honesty. Perhaps it had been one of those days when there hadn’t been enough adults to talk to, and she just wanted to be seen.

They’ll stop one day, I know. The baby will go to nursery, and we’ll spend less time on the bus. The baby will become a toddler, then a child. We’ll slide out of the realm of easy conversation subject, no longer keepers of a passport out of polite silence.