Six years ago, in a small pool that took up most of our dining room, our eldest child Isaac was born. As a father, I’ve been floundering around trying to keep my head above water ever since, watching as my boy has navigated a course from static to crawling, from crawling to walking and from walking to doing a passable impersonation of Mo Farah.

As a parent, I am duty-bound to say without the slightest hesitation or hint of equivocation that my first-born is incredible, unique and destined for great things. All these things are true, of course – did you expect me to say anything else? – but what pleases me most is not his intelligence (he takes after his mother), his sociability (he takes after his mother) and his drive (you get the idea) but the fact that he is – the vast majority of the time – a happy child.

This morning he was as pleased to receive a bag of Jelly Belly jelly beans – he’s a sweet snob who turns his nose up at pale imitations – as he was to unwrap his latest gadget, a second-hand Nintendo DS Lite. And hopefully tomorrow he’ll get out on his new bike and love it as much as the one he outgrew months ago but has been riding with vigour anyway.

Sure, he has his moments of foot-stomping drama-queen-itis and end-of-the-world misery, just like any child does. But his general disposition is one of a boy who is mature, thoughtful and unselfish, who is always quick to volunteer a cuddle and who has a voracious appetite for learning, discovery and, er, Super Mario Kart.

Six years old! I’m still finding it hard to get my head around, really. Six years from today he’ll be in secondary school – another six years and he may be making decisions about universities. That feels like an awfully long way away today – and yet I rather suspect it will be here in a flash. Where on earth does the time go?

Happy birthday, my amazing not-so-little-any-more boy.