Tetta was my neighbour; she was twelve days younger than me and my best friend in the world. It was the summer holidays. We were happy. We were feral. We were nine years old and the best entrepreneurs in north London. We had only one objective: to buy as many sweets as possible.

Tet and I had several little businesses going, aside from a little light shoplifting. Outside her mum’s house was a massive bay leaf tree. We’d climb up it, pick the big leaves and sell bunches of twenty for five pence a pop. Or some days we’d pilfer things from around the house and set up stall on the bridge at the end of Gloucester Road. We’d stopped doing that when Tet’s mum went ballistic on discovering we’d sold her silver knocking ball thing and her gold wedged boots. (We never mentioned the pretty, sparkly ring).

In the afternoons, after working up a sweat skateboarding, we’d pop into the Holiday Inn at Swiss Cottage. ‘Daddy’s in Room 42,’ we’d say breezily if anyone asked. But they rarely did. So we’d go in and avail ourselves of the facilities. They had a fancy shoe-shiner on the first floor and an okay pool, and lovely little soap sachets on the cleaner’s trolley. We’d nick the tiny bottles of whisky and vodka and we’d sell them to the old tramp in the skateboard park.

One particular day we were walking back from the Prince of Wales swimming pool, stuffing our faces with Fruit Salads, Love Hearts and Curly Wurleys, having just begged a little money by fashioning a baby from our swimming things, when Tetta informed me about a new theory she had: everything in the universe bounces. ‘Absolutely everything,’ she said emphatically.

I wasn’t quite so sure about it. Elephants, for example – I didn’t think they bounced. ‘Oh, yes they do,’ she said and promptly picked up a brick from a builder’s load we were passing, climbed up the railings of the nearest house and chucked the brick as hard as she could on to the pavement. I watched mesmerised as it broke into a hundred pieces, smashing the basement window of the house. As we sprinted away she turned to me, ‘Did you see?’ she beamed. ‘It bounced!’ Ah, bright ideas and happy days…