My earliest memory, I believe, dates from 42 years ago on November 2, 1970. It’s dark, I’m lying down and my father is bending over me, saying “and tomorrow you’ll be two”.

I think this is a true memory. I’ve always thought it to be so, and I seem to have recalled it many times throughout my life, particularly as my birthday approaches.But whether this has refreshed it, or merely rebuilt it and I just remember my own construct, I can’t be certain.

According to Wikipedia’s entry on childhood amnesia (the phenomenon that adults cannot remember early childhood clearly), "memories from early childhood (around age two) are susceptible to false suggestion, making them less trustworthy". A bit like Wikipedia.

I mentioned my memory to my dad some time ago and he doesn’t believe it happened, but that could be because he doesn’t believe I could remember it. I think it is more or less accurate, but I may have altered some details. I’m pretty convinced of the words spoken, but my father’s face is blurry – it’s undeniably him but I’ve no clear picture of him in his late 20s. Also, I think I’m in a bed, not a cot, and in my own bedroom: that’s dubious because of another early memory I have, of being just a little older and breaking out of my cot, which was in my parents’ bedroom.

That apparently quite regular escapade is still occasionally the subject of an amusing family anecdote, but I'm convinced of my memory of doing it because I remember what it felt like. One end of the cot was an integral blanket box, the outer face of which was a curved roller door. I remember clambering onto it from inside the cot and then the discomfort, the pressure on my ribs, as I spun myself round on my chest on its angular surface so I could slide down over the roller. It hurt, but not enough to stop me doing it over and over again. I think it would be hard to construct a memory of physical sensation like that.

And now I've just turned 44. How very middle-aged. Still, it’s fashionable to be middle-aged – everyone I was at school with is doing it, even the cool kids.

I’m not quite sure when you become middle-aged. Not halfway to three score years and ten, anyway – 35 is young these days, and counting anything by Biblical reference leads to nonsense about the Earth having yet to reach its 6000th birthday and our ancestors having the opportunity to own pet stegosaurs.

The generally-accepted gateway to middle age seems to be at 40, and that is closer to the halfway mark suggested by UK National Statistics, which is just about 80 (except for viewers in Scotland). So by that token, I have been middle-aged for four years, or ten per cent of my life. But these averages don’t really mean much, middle-age is more a matter of mind than of numbers. I think it happens when mortality first bites, at that point when our sense of invulnerability quietly slides away and we see the final curtain flapping in the wind, even if it is still some way away.

In my case, that was just about a year ago. In the run-up to my 43rd birthday various doctors interviewed, examined and scanned me to ascertain why I had thrashed epileptically across the office floor at the start of October; a week later I went for my first MRI, and disturbingly quickly after that had what is probably still the worst day of my life so far - November 16, 2011 - when I woke up to a phone-call telling me my lovely wee Gran had died, and then went into hospital to learn that I probably had a brain tumour.

Less than a week after that I was chatting with neurosurgeons who asked nicely if they could cut into the side of my head to check. And on December1, they did.

Just days before that operation I started this blog, so everything that followed - the whole unpleasant business of being told that I did have a tumour and it was likely to try to grow a new head, having to tell other people, and then the vaccines and radiation and chemo, the tiredness and sickness and hair-loss – have all been well documented.

So if you've read at least some of that, you'll realise that on the whole 43 hasn't been a great year for me. But while I hate to cast myself as relentlessly optimistic – I do like to examine all available silver linings for clouds – I can’t help seeing the upsides to this year: I married the love of my life, had a couple of great holidays, and my new-found sense of mortality reinforced my sense of how precious time is, which has given me greater ambition to do things for the fun, satisfaction or hell of them (more on that in later posts, perhaps).

Wish me a happy birthday. And if you want to make it happier, donate some money to The Beatson.

They’re the reason I’m feeling good and ready for another year, after all.