Damn him, he was right. At midnight on my 21st birthday, this fella sat me down in front of him, crouched very close and told me that because he was doing this, I would always remember that moment, I would always remember him.

It felt a bit invasive, really, and I have some small pleasure in telling you that I remember the moment, I remember the room, the house, the woman next door I had a crush on, I remember everything except who in the hell he was. I can’t quite recall his face, can’t quite forget it either. So he’s in my head but as if with one foot in my noggin, one foot not.

I can’t decide if that’s better than my 30th of which I can’t remember a single thing. I’ve been pretty good ageing one year a time and in the right sequence but if you told me I’d skipped my 30th, I’d believe you.

My 40th is easy: I was in shock. Not because of the age, I’m not one of these people who get bothered by a number, but because of my wife Angela Gallagher. My teenage self would be startled that I was married, my sophisticated 40-year-old self was agog that she was still with me, but that wasn’t the shock. The true, honestly put-me-into-trauma-shock was that she surprised me with a trip to New York City. It’s my favourite place in the world and I did not see that coming.

Listen, I think you see where this is going and I think you see full well that actually I am one of those people who get bothered by a number. I wasn’t. But I am now. As I write this, I’m 49 and when you read it, I will be at least 50. Could be older if you’re a slow reader or if all that survives of the 21st century is this chat with you. But at least 50.

I have found it hard. I am finding it hard. I could do you a CV and it would sound okay. I can tell you that I am half the writer I wanted to be but, truly, I’ll take that – so long as this isn’t the end and my writing is still in progress.

It’s not even as if I simply feel old. I do, though. I was working with a school recently when an 8-year-old called me a ‘random unfamous guy with no dress sense’. I’ve also recently been described as a looking like an English teacher or ‘everybody’s favourite Geography teacher’. One guy thought I was a professor and didn’t mean it as an insult, I think he even fancied me. (Still got it, eh? I’m asking you seriously: I can’t tell. Can never tell.)

And none of these things are bad plus the fact that people have descriptions of me is profoundly flattering. Even the bad opinions, it means I am somehow in people’s heads. Briefly, no doubt, but there. Considering that I just assume that when I’ve left a room, I am gone from people’s minds, I am warmed by all this. Warmed by English or Geography, warmed by it all.

Only, they’re wrong. How can they be so wrong? I’m not a professor or a lecturer or an adult: I am 17 and I haven’t done anything yet.

That is a big, recurring thing with me that does not need a 50th birthday to be in my mind: the sense that I have only just started, that I have so much to do and, yes, not a giant amount of time left in which to do it.

So clearly I should get on with it, shouldn’t I? Except I wanted to tell you something. On my birthday I will be in Paris, my other favourite place in the world and while I get that these are not great times for the city, the time and the space means a lot to me.

And so does this. When I remember my 50th, it will be a memory of me crouching down to look you in the face and telling me that I will always remember talking to you right here.