Zac is 18 months old today, and looking back over the last few months it’s scary quite how fast he’s growing and developing.

A few random observations.

He started talking quite early on, but he continues to amaze me with the breadth of vocabulary he now boasts. One morning recently, for instance, he very clearly asked for “mango”, to add to an ever-growing food-related repertoire which includes “cheese”, “toast”, “apple” and “biscuit”. His evening bath is frequently accompanied by a repeating mantra of “bubble, bubble, bubble, bubble”. He regularly entertains staff and parents at nursery by waving and proclaiming “buh-bye!” whenever anyone goes by. And part of our bedtime routine has traditionally been to sing ‘The Grand Old Duke of York’, where he completes the relevant lines with giggling cries of “up” and “down”.

Naturally, he understands an even wider range of words too. If Heather’s in the shower, she will ask him to pass her a towel, and he does. If asked to flush a toilet, he will. When asked to identify dogs, squirrels, ducks, cars, aeroplanes, clocks and assorted other items in books, he will scour the page until he finds them. And he has understood the word “no” for ages, although of course he chooses to ignore it most of the time!

He’s been walking for about four months now, but it’s quite something to see how quickly he can move when he sets his mind to it (which is often). His balance is coming along nicely too; whereas a couple of months ago he was very much a wobbly toddler, he is now much more confident on his feet, rarely falling, bouncing off obstacles and continuing on like a running back bursting through a crowd of would-be tacklers.

Most gratifying of all from my point of view – partly because it’s one of those activities which has very much become a father-son thing – is his response to music, whether it is nursery rhymes or pop music. We have spent many hours together, often first thing in the morning or last thing before bed, singing, clapping or generally just chilling out; music is usually a foolproof way of calming him down when he’s throwing a strop. He plays drums on upturned saucepans, recognises familiar songs after only a few notes, claps along in time, and even sings ‘Twinkle, twinkle, little star’ spontaneously and unmistakably. It’s only a matter of time before he starts critiquing my tendency to be slightly flat when singing to him. (Hmm, Simon Cowell in the making …)

There are so many wonderful things about watching him grow, expecially at this age where the pace of development is so fast it can be difficult to keep ourselves one step ahead of him. Whatever happened to the helpless little thing who used to do nothing but drink, cry and fill nappies?

No longer a baby, very much a boy.