That winter's day in the park, although we weren't to know it, was to be the last time I ever played football with my son. The memorable two-a-side match featured Peter and his cousin William, with a combined age of 20, against his uncle and me, each aged more than twice that. The half-time score was: sons 15, puffed-out parents one (and a controversial goal at that).

There was no second half or injury time, just injury – to uncle's ankles, which he was bound to sprain in those venerable mountain-walking boots. The 10-year-olds soon promoted themselves to playing with more able-bodied opponents, ie other boys, and I realised the final whistle had now gone on lads v dads. Our Match of the Day was now my Match of Yesterday.

"It's as if that little boy has been taken away by aliens," my late wife once remarked. Ruth did not believe that a spaceship had whisked our son away to the Earthling Museum on Planet Zorg and substituted a 17-year-old rave-music-mad Zorgling. She meant that he could just as well have been the victim of an alien abduction and substitution, as he grew from 3ft to 6ft, toddler to teenager, paddling-pool to surfboard.

Ruth was particularly conscious of the passage of time, as it was a commodity that, thanks to a brain tumour growing slowly but inexorably, she possessed less of than the rest of the family. As the children became more able, she became more disabled. Yesterdays are carefully noted when there aren't too many tomorrows. I took the photographs of the children as they grew up, but it was Ruth who stuck them carefully in the albums, noting down the time and place.

You are always aware of a "first" when it happens. There are embarrassing baby-books with blank spaces parents can fill in, labelled "My First Tooth" or perhaps "My First Projectile Vomit". You know when a child produces its first painting, or splodge. You keep the artwork in case Tate Modern wants it for a major retrospective in later years.

A "last", however, can come and go without registering on the radar. I have never come across a "Book of Lasts" with sections to be filled in on final footy knock-about or ultimate nappy. There is no record of the last time I yelled: "For the last time, will you turn that television off!" Nor is there any record of the last time, perhaps years before, when anybody did obey that particular command.

On the evening when I read the last bedtime story to the youngest child, I was not aware that this was anything more than another instalment of a Swallows and Amazons novel.

"I think I'd like to read to myself from now on," she said politely when I appeared after bathtime the following day, Arthur Ransome in hand. And that was it. She had closed another door and, indeed, book. If I'd realised in advance how significant the previous evening was going to be, I'd have hired a brass band and got Michael Morpurgo in to do the reading, with a film crew to record it for the family archives.

I had been reading to one, two or three of them to send them to sleep every night for the best part of two decades. The books went from the first child's wordless picture-story to the third child's practically grownup novel. I know parents are supposed to read to their kids, but sometimes my performance was too successful and it was me who entered the land of dreams first. Here, I would find myself reading from a more Freudian sort of book and would be awoken by a cry of "Why did you say, 'Lots of naked ladies', Daddy?"

The first last, if I may put it like that, must have been when our oldest was still in her cot. Among the soft toys, she was given was a cuddly mouse. By chance the next few presents were mice, which she enjoyed so much that friends chose mice deliberately to add to the gathering of rodents that I had to line up on her pillow. She couldn't count – certainly not up to 17 – but she protested loudly if there were only 16 at bedtime.

"There are too many mice!" she suddenly declared one evening and hurled them to the floor. After that, her pillowtalk was with teddies and badgers only. As I had got used to gathering the mice from all over the house, it would have been good to have known on the previous evening that this was the final round-up for those small, whiskery toys.

Although she may sound rather high-handed in that instance, she proved very obliging in a later last. This involved her endearing mispronunciations, such as "marleyblade" for "marmalade" and "matato" for tomato. "Brilliant!" we thought. "Why not Orlando the Marleyblade Cat? And 'You like tomatoes and I like matatoes'?" Children's author Kathleen Hale and the Gershwins missed a trick here.

After a while, her mental spellcheck kicked in and she enunciated those words as clearly and correctly, as if she were auditioning for an infants' branch of Rada. Then, realising the pleasure her accidental mispronunciations had given us, she would occasionally mangle them on purpose for our delight. Until she didn't any more.

When was the last time I chose the restaurant? I can remember clearly the first time I didn't, which was on London's South Bank, when I meekly followed the (by now pretty grownup) youngsters in and out of different eateries, which they instantly declared to be too crowded or too deserted or too expensive or too cheap, or to have menus with too many mushrooms or not enough mushrooms. However, I did have a part to play; guess who picked up the tab?

Some firsts also involve a last. When a child climbs to the next rung on life's ladder, it means the previous rung is no longer going to be trodden on. The first time they go solo in a canoe on a boating lake means they won't be crewing a shared rowing-boat with you any more. The first time they send their own Christmas cards means you won't be adding "… and Peter" (or whoever) to yours.

It is great when we parents at last see the small feet of a trainee cyclist pedalling at speed and the bike launched into independent orbit. After weeks of sprinting bent double like Groucho Marx doing a runner, we get our backs back. The downside is that the child seat on the parental bike will be empty from now on. Those companiable times on the same two wheels have reached the end of the road.

This is also true of four wheels, when teenaged children pass their driving tests, an achievement that, unlike late learners such as their parents, my lot managed first time. They no longer needed my services as a late-night minicab driver: "Pick me up from No 23 – follow the incredible noise and the policemen." This is mainly a plus except that – call me needy, if you must – it's nice to be needed in a Home-James-and-don't-spare-the-horse-power sort of way.

The first child's first term at university is a major milestone, a fingerpost pointing away from the family home. We dropped ours at a far-off seat of learning. I remember as if it were 1992, which it was, our daughter shrinking to a disappearing dot in the rear-view mirror while we drove somewhat tearfully towards the motorway.

It hit me that the previous night had been the last in which she would have slept in the family home as her main place of residence. From now on it would be student accommodation and then a shared house, to be followed by the whole mortgage bit.

It was no thanks to her parents that she ever reached university to study science. I drove her there, of course, but it makes a mockery of heredity that any child of ours (Ruth was a social scientist and I probably did English) should achieve three science A-levels.

It would have been early in her sixth-form career that we went to the last of her parents' evenings at which we could understand what her teachers were on about. "Your daughter," said one of them, "spends 40% of her time …" He paused. What was he going to say? Looking out of the window? Making Molotov cocktails in a test tube? "… Doing chemistry, 30% on physics and 30% on maths." I proudly worked out that this added up to 100%, but that was my peak as far as her parents' evenings were concerned. I had helped with primary-school homework but now I was struggling over anything involving figures or the periodic table (whatever that is – something to do with weekly magazines, maybe?).

"Mummy, what's that language they're speaking?" asked our youngest, overhearing her sister and fellow A-levellers revising in the kitchen.

"I think it's chemistry," Ruth replied. This was the subject I had failed at O-level and she hadn't even taken. She was quite pleased she could even recognise it.

To give myself due credit (in case no one else does), I helped all three children with their English GCSEs, but after that stage my sole contribution on the homework front was to suggest that they got on with it.

After O-levels my class had been told to read Jude the Obscure for light relief. One of its least gloomy bits, ie in which no one hangs themselves, is the moment when the young hero realises he has shifted from being at the circumference of his own life, with little impact on what happens in it, to being bang in the centre. He is now responsible for what goes on and what goes wrong. And when children are at the centre of their own lives, their parents aren't. They then start to supervise the lives of their parents. This parent, anyway.

"What are you wearing?" the children demand. They buy me intellectually demanding books. In the period between the death of my wife and the appearance of my partner, they scrutinised any ladies they happened to find me with.

That is not a complaint. I am more fortunate than a friend and his new partner who came to the cinema with me but could not stay for a drink afterwards. He explained that this was because of his son, who at the time disapproved of the relationship: "He hasn't given me a late pass."

No, this is not to say that I wanted – or Ruth would have wanted – our children's childishness to be preserved in aspic as they proceeded through school, university, employment and, in one case so far, parenthood. Rationally, I approve that they have been reading to themselves for decades. On balance, I am glad they paddled their own canoes and pedalled their own bicycles.

When I was still living at home (in, as it happened, a converted hen-house, but we war-babies didn't complain), my mother informed me in a very adult way that it was fitting for children to grow up and move away. Yet she was clearly upset when she visited me in my first flat, which showed that I had done just that. She was enormously consoled when I eventually had my own children for her to play with.

Similarly, a major consolation for all my lasts is the new batch of firsts, which I (but sadly not Ruth) have been and will be enjoying: my grandchildren's first words, first books, first bikes. I'm even looking forward to their first chemistry lessons. And will my grandson and granddaughter be aware that each of their firsts represents the end of an era for their parents? No, it will be the last thing on their minds.