The second hand of my watch is half-way round - 30 seconds to go until the insurance certificate becomes valid.
I put on my orange crash helmet and imitation leather gloves. Fifteen seconds. Tilting the bike on its stand, I start it the semi-cool way, by kicking down on a pedal. From a distance, it might conceivably appear as if I was starting a real motorcycle. Nine o'clock exactly, or as exactly as is possible in this pre-digital watch era.
I sling my leg over, knock the prop-stand back up with my heel, blip the throttle and I'm off. There are tears in my eyes, from the wind rush rather than the emotion, but my heart is soaring as a sense of freedom makes me feel that I never want to stop and get off. It is the day after my O-grade physics exam.
In Lanark, I forget to turn off the fuel tap when I do eventually stop and the engine floods. I remove the single spark plug and dry it. The bike restarts, and somehow this is even better than if it hadn't broken down and needed me to fix it. On the way back home, I'm sure I went over 30mph several times, but the Raleigh's speedometer wasn't working so I can't swear to it.
I can only get so far from this memory before it hits me again, like a brick tied to the back of my head with a length of elastic. More often than not, it's the oily smell of a two-stroke engine spluttering in the rain that does it.
Recently, it was my daughter's own 16th birthday. We booked her a party at the pizza patio of the local Italian restaurant. The owners were happy for us to festoon the place with balloons and plenty of photographs of her when she was a toddler.
Far from being embarrassed by this, she had a ball laughing at herself. I hope she always feels this way. There is a chance that she will work in childcare. If she can look back fondly and unselfconsciously on the things that she did as a child, it will help her to relate to the youngsters themselves.
It took me a while to get there, but I can now smile rather than cringe at the memory of falling off a Honda in front of the school minibus as I tried to impress its occupants with a racing turn on the oil-soaked Tarmac of the local bus stance.
Gregor Steele remembers his 17th birthday (Lambretta scooter) and his 18th (can of Tennents lager) well, too.