My daughter turned 17 earlier this month. In the days leading up to the big day I told her about how I spent my 17th birthday, or more specifically the evening of that day. I don’t recall much about the morning or afternoon, a regular Friday at school at the start of my second year of Sixth Form.

The day was unmemorable but the evening was memorable from a mathematical perspective. My old Maths teacher and I were both born on 21 September, 17 years apart. On my 17th birthday, which was his 34th birthday, we celebrated the fact that he was exactly double my age. He had been my Maths teacher the previous academic year but was taking a sabbatical, studying Philosophy. In those days, like many teachers at school, he frequented The Old Ship in Hammersmith, beside the river. I only went there a handful of times (too many teachers in the place) but I met up with him that night and we toasted our mathematical milestone. It’s the only time that I have had a drink with someone on the day that they were exactly twice my age. It will not happen again. There is nobody alive who is that old.

We had a couple of pints of Guinness and he introduced me to a few of the other regulars at the pub. One of them, Derek, was taken by the mathematical link. He congratulated me and bought me a drink, a regular pint of Guinness. At the same time he bought a more enhanced drink for my old teacher, who was drinking from a special two-pint jug. In addition to the quart of Guinness he added four shots of vodka. I left before the jug was drained and headed down to the Rutland, near Hammersmith Bridge, to meet my mates. It had become a regular Friday night meeting-place, with its pool table out the back and bar billiards in the main bar.

My daughter’s evening in celebration of her 17th birthday was far more sedate. She had been to a well-known hamburger restaurant with her school-friends in the afternoon, finished her homework before 6pm, and we had a takeaway from the nearest Hare & Tortoise, a regular birthday thing since 2020. She and my wife had been watching the final series of the BBC comedy “Ghosts” and we all watched the final episode together.

I was in bed before 10pm, the earliest I have ever turned in on one of my daughter’s birthdays. Most years I have celebrated with a combination of champagne and wine gums. It was how I toasted her return home from hospital 24 hours after she was born. Last year, on the equivalent date, I stayed up until 3am with my sister drinking champagne, and had a brute of a hangover the next day. No such nonsense this year. It was all much more civilized, in keeping with how much more sensible my daughter is at 17 than I was.