Eventually, my wife said: "Oh, let's just go to the coast. It's not as if I even like trains anyway."
I pulled into a quiet road, stopped the car, and turned off the engine. "What did you say?" I said. My wife repeated her assertion, albeit less confidently, and this time there came a great shout of protest from the back seat. And so the matter was settled: we carried on looking for steam trains.
It was a tricky moment, however; the clearest yet manifestation that trains divide our family along gender lines. The boys and I read train books for hours, and talk about them late into the night. (Well, early into the night actually, because they go to bed at 8pm.)
Our copy of Things That Go always falls open at the locomotives page now, and we have long discussions about issues arising out of Thomas The Tank Engine books, such as "Are all diesels horrible?" or "Is Thomas a big engine or a little one?" (The answer here, by the way, is relative. He's clearly a good deal smaller than Gordon, yet a little bigger than Percy.)
A love of trains is in my blood. My father worked on the railways for 40 years, and had a Privilege Ticket which enabled him to go anywhere free, and in first class to boot. So frequently and widely did he range across the network that if a ticket inspector approached him, say, somewhere west of Bath, he wouldn't insult my father by inspecting his Privilege Ticket. He'd just nod instead, and say, "How're you doing, Bill?"
As a boy, I too had free train travel and went first class, much to the irritation of the sleek businessman alongside whom I sat whilst reading the NME and eating crisps. Once, I went from York to Aberdeen in a day, which meant approximately 16 hours on a train and 17 minutes, I think it was, in Aberdeen. I had a lovely time and I can see my sons doing similar things a few years from now.
And yet my wife's outburst in Sussex prompts the question why. Why do men like trains? Why do I never see a woman browsing in my favourite rail bookshop in search of titles such as GWR Locomotive Allocations for 1921 by I Harrison? or North Staffordshire Waggons by GF Chadwick.
There are two familiar theories: that trains are phallic symbols; and that the appeal of railways is the appeal of systems, the displacement of emotion by organisation. Both of these tend to support the idea that the train enthusiast is a sinister inadequate, an implication which, speaking as a train enthusiast (I've never quite been a spotter), I am unwilling to accept.
I personally think that the appeal of trains to men is not that they somehow boost our machismo. It is, on the contrary, that they represent an un-wimpish respite from the stresses of machismo. They are about escape: a lulling rhythm; looking out of the window whilst your coffee goes cold and your sandwich curls; time to think. Trains, unlike cars, are conducive to contemplation and spirituality. It's no accident that a vicar wrote the Thomas books, or that the Titfield Thunderbolt, in the railway film of that name, was manned by an entirely ecclesiastical crew. But how, my wife asks, can this theory encompass two little boys aged two and three? To which I - a former boy with a pretty good memory of what it was like - say this: "You would be surprised."