Among the many useless but consoling facts I’ve hung on to at the expense of real knowledge is the telephone number of my best friend from high school. I can say it in my head – 612505 – and, like a combination lock, it throws open the door to a memory of me sitting on the stairs after school, yakking to the person I’d just said goodbye to on the bus. Given it’s more than 30 years since I used that number, I have to assume it will stay with me – along with the lyrics to the Cadbury’s Roses ad from 1983, the name of the fictional head