My son Jacob is leaving home on Saturday to start a four-year course at university, 160 kilometres away from where we live. Spanish with International Management. I am unequivocally thrilled for him. But for myself, less so. In fact, not to put too fine a point on it, I'm scared.
Jacob has had a meningitis vaccination in preparation for student life, but there's no medication you can take to ward off so-called "empty-nest syndrome". My wife Jane and I just have to wait and see how bad it is, then learn to cope. I've a feeling that she'll be OK, but that I might struggle.
Fathers are not meant to mourn the empty nest like mothers do. The narrow domestic conventions of the Fifties and Sixties have changed, of course, to accommodate all sorts of family arrangements.
As a child myself I knew hardly any working mums, let alone stay-at-home dads. But even in this day and age it's usually the mother who has nurtured the chicks, so she is the one expected - indeed, entitled - to be left bereft when the fledglings are finally old enough to fly.
And where does that leave us, the fathers? As towers of strength and comfort, naturally.
But what if we don't feel very strong? What if it's us who need comforting?
Jacob (aka Jake) and I aren't pals. We're father and son, which is different. But we play golf and tennis and snooker and darts. We watch football and films together. He shows me funny YouTube clips that I would never have found on my own. We have lots of laughs. Partly because he's the youngest of our three children and it wouldn't seem right with the other two, and partly to indulge what's left of the big kid in me, I still have occasional mock-fights with him.
"I won't have anyone to punch and wrestle with when he's gone," I lamented to Jane the other night. There was a brief but telling pause.
"Yes, but I don't think Jacob particularly likes that," she said. "He hasn't liked it for about five years."
I was crushed. "But you can always go and visit him at university if you want someone to wrestle with," she added hastily, sympathetically, as if to a disappointed toddler. It was too late.
I was reminded of the time about ten years ago when she told me, gently, that it was no longer appropriate for me to walk into my adolescent daughter's bedroom without knocking. Fatherhood is full of small moments like that, when you have to start doing things differently.
But empty-nest syndrome is not about doing things differently. It's about not doing things any longer. Or at least, not until they come home for Christmas, but there's no point pretending that life will ever be quite the same again.
Of course, I wouldn't have it any other way. It is time for Jacob to start the next phase of his life, just as his sister and brother did before him. In the best possible sense, we have raised him to want to leave home.
Shortly after Jacob was born 18 years ago, we had a non-religious naming ceremony, at which his 'godmother', the TV presenter Sian Williams, read from the works of the Lebanese poet-philosopher Khalil Gibran.
There was a line that has stuck in my head ever since, about parents being the bows from which children 'as living arrows' are sent forth. The stronger the bows, the further and straighter the arrows fly.
That's a lovely, comforting image. But will it be enough to sustain me when I'm trying to hit bullseyes and sink putts on my own? I fear not.
My emotions where my children are concerned always take me by surprise. I'm not, in the general scheme of things, what you'd call a softie. Yet my children can turn me into a human waterworks plant without even knowing it.
When our middle child Joe took a gap year three years ago, and set off to spend four months backpacking round South America, I saw him on to the Heathrow Express at London's Paddington Station.
I had spent ages reassuring Jane that he would be fine, but it wasn't anxiety about his safety that hit me like a ton of bricks seconds after I'd hugged him and started walking back down the platform. It was something else, something indefinable, something about fatherhood. Whatever it was, by the time I got to the concourse I was blubbing like a baby, with people glancing at me and then away, embarrassed.
Similarly, when Jacob went to collect his A-level results this summer, then phoned me to tell me he'd bagged an A-star and two As (clever lad), I was elated but not at all tearful.
Moments later, however, Jane called me to ask if I'd heard, and I found myself instantly awash, unable to utter a word, just making a strange noise - like a chicken in mid-lay, she later described it - for so long that she thought I was having some kind of seizure.
I was felled by the same kind of delayed reaction when Jacob was 18 months old, but for dramatically different reasons. It's a long and painful story but I'll keep it short.
We were on holiday in Spain, having a wonderful, convivial lunch with friends, in a restaurant overlooking a beach on the Costa de la Luz. Suddenly I noticed that Jacob had worked his chair over to the open window, from which there was a sheer drop of 40ft to a rocky ledge below.
He was leaning out, and by the time I got to him he had toppled head-first through the window, a blur of little blue sandals and yellow socks. It was a miracle that he survived at all, let alone that he suffered only a few grazes. It is not something I care to dwell on, even now. But I do remember that my racking tears of shock and relief came long after Jane's.
Jacob is no more or less precious to me than my other children, but that episode made me feel intensely, viscerally protective towards him. Only he doesn't need my protection any longer. He's a man, and off to start his manhood in time-honoured fashion, by drinking lager in the student union, like I did.
So where will all that leave me when, this weekend, I confront the empty nest? When our daughter Eleanor left to go to Bristol University five years ago, we still had two sons at home, so that was different. Moreover, she was a girl. I missed her, but not because I spent lots of time talking and watching and playing sport with her, because I didn't. Gender makes a difference, too.
And yet, the real loss this time should really be Jane's. She was the one whom Jacob reached out to all those years ago when, after hurtling down the steps to the beach below, we found him in the arms of the Spanish woman who had picked him up. And she's the one he still reaches out to when he's in need (albeit mainly of clean clothes).
She is the one who has made a 23-year project of all our children, taking them to school, helping them with their homework, teaching them to cook, replacing their lost blinking iPhones, always dependable, always there.
So I do not underestimate how hard Jane is going to find it in this newly empty nest of ours. She will feel Jacob's absence deeply, and has already admitted to being fine during the days as she whisks him off to Ikea to buy bits and pieces he'll need, and gives him a crash-course in how to perfect a spaghetti carbonara, but then jolting awake in the middle of the night with the sudden, painful realisation that her baby (nigh on 6ft of him, but still her baby) will soon be gone.
However, mums have a powerful support network of other mums. Jane can pour her heart out for hours to her friends and they will dispense sympathy, advice and strong coffee. If it's not too rude to extend the empty-nest metaphor still further, they will cluck supportively.
For dads, there is no such network, nobody to cluck with. I wouldn't mind a bit of clucking.
I might go down the pub and spend two minutes telling my mates how much I'm missing Jacob, but if I get anywhere close to five minutes then someone will change the subject to the football, or Donald Trump, or anything, really.
I suppose I have a job to think about. I have always had my work as a journalist and author to distract me from the challenges of fatherhood, taking me away from home, or taking me away even when I'm at home, into my little office eyrie, at a (sometimes welcome) distance from the happy, agitated frenzy of family life. But I've always known, as I hope they have, that I was doing it for them.
There's a sweet online video about empty-nest syndrome, illustrated by the comings and goings in an actual nest, as a mother-robin sits on her eggs, sees them hatch, feeds her babies and watches them grow.
Then, finally, the father-robin comes back with a big juicy worm, only to find that they've all gone. You wouldn't think it possible for a small bird to look utterly disconsolate, but he does.
For years, nobody had a name for empty-nest syndrome, and therefore nobody really acknowledged its universality. Even when they did, its impact on fathers wasn't much considered. But it did get some rare attention, in this country anyway, as a result of Jack Rosenthal's 1997 TV play Cold Enough For Snow, which was inspired by his own experience of going to pieces when his children left home.
In the drama, a sequel to the acclaimed Eskimo Day, a father in Blackburn has a nervous breakdown when his son leaves for Exeter University. I watched it again this week and for me, now, there is a very poignant scene in which the dad goes to a football match, as he always used to with his lad, but then turns away at the turnstile. Alone, it seems like a pointless exercise.
Unexpectedly, it is his homely wife (Maureen Lipman, who was also Rosenthal's wife in real life) who uses their son's absence to grow and thrive, taking a degree at the local technical college.
Maybe that's what will happen to us. I confess to encouraging Jane to take up golf now that Jacob is about to leave. Perhaps she could try her hand at darts and snooker, too. And start finding me some funny YouTube clips.
I'm joking, of course. This is not just about me, about my void. But it is very much about us, a husband and wife who have shared our home with our children for almost all our 24 years of married life.
We are on the cusp of a new phase just as much as Jacob is, and we're already trying to embrace it; we've just booked a long weekend in the South of France, which we would never have done when he was at home.
But our new life together seems bound to throw up challenges as well as pleasures. What will become of cherished family traditions, like the Sunday roast which Jane insisted on cooking even when there were just three of us? I'm pretty sure that was mostly about feeding her young. She won't want to peel parsnips just for me.
Nonetheless, we will have to talk more, do more, play more. It could be a boon to our sex life - no danger of an afternoon liaison being interrupted by that indignant teenage bellow 'Where are my football boots?' - but then we might miss the frisson of adventure.
For so long, our children's needs and very proximity have determined the rhythms of our relationship. Now that's about to change for ever. And in all honesty, that scares me, too.
Sorry, says his wife, you're wrong
Jane says: All week I've been busy. Shopping with Jake. Washing his clothes. Advising him on what to pack. Staging crash cookery courses in the kitchen, so he can rustle up the tastes of home in his student kitchen. Too busy to think about next week, in fact: the first week of many that he won't be here.
But last night, and the night before, and the night before that, I woke up with a start in the early hours, and my mind was instantly flooded with sorrow at what I'm about to lose.
And that's how it's been. Positive and productive by day, then engulfed by sadness in the pre-dawn hours. Get a grip, you might say; he's only going to university.
This is true - and, of course, I know it. But I've made a career out of raising our kids, and I feel like I'm about to be made redundant. Meanwhile, Brian's working week will remain exactly the same.
So while I sympathise with his empty-nest anxiety, and his uncertainty about how life will look when it's only the two of us again, I just don't think his sense of loss will be as great as mine. It just won't.
The last chick is about to fledge, and I'm dreading the silence on Monday, when Brian's in London and I'm in Herefordshire and Jake's gone.
Brian's right, though, that I have a tried-and-tested support network. Lots of female friends who've either been through what I'm about to, or are going through it with me.