It is raining in central London but, at a shop near Waterloo station, trade is brisk. Ian Allan Book & Model Shop is a focal point for trainspotters, bus lovers and aviation enthusiasts. It is the last specialist transport shop in the country, but on October 31 it will close.

For the shop’s devoted clientele, it is devastating news. “The only other place to go is Foyles, and their transport section is two shelves,” said John Scott-Morgan, 66, a customer since it opened in 1987. People travel here from all over the country, said Kerry Foster, 56, the shop’s manager. “One of our clients comes from the West Country, several others from Scotland and Wales,” she said. Others journey from abroad to get the thrill of buying models in the land that invented the steam locomotive. One teenage boy comes from California with his parents every year. He calls it “the best shop in the world”, Foster said.

Nick Allan, director of the company founded by his grandfather Ian, said Covid-19 had hurt it: “Our average customer is over 50 and we don’t think the average 50, 60 or 70-year-old is going to hop on a train to London anymore.” He said the closure was also a sign of waning interest in transport history: “We are finding there is not as much interest with the younger generation because of iPhones and computer games.”

One teenage boy comes from California with his parents every year. He calls it “the best shop in the world.”

In the past decade the company has closed shops in Birmingham, Manchester and Cardiff and sold its magazine and book publishing arms as sales declined. How you feel about this will depend on your point of view. Here, I should declare an interest. My father, 70, is a railway enthusiast. As a teenager, I spent more weekends than I care to remember standing in the rain on a platform trying to hide my face and smother my shame. If there is a brutal regime looking for new ways to torture young women, asking them to pick up a copy of Railway Modeller on the way home from school is a good start.

Yet it was not all that long ago that trainspotting was a national obsession, and Ian Allan was the one who kicked it off. Allan, who died in 2015 at the age of 92, worked as a clerk for the Southern Railway’s publicity department at Waterloo during the Second World War. He had the idea of compiling a book containing the technical data of the engines and listing them by number. Remarkably, given the constraints of wartime censorship, his first booklet, ABC of Southern Locomotives, was published in 1942 and sold out immediately.

The hobby took off in the postwar decade. At its peak, 250,000 schoolboys joined the Locospotters’ Club, gathering on platforms or at the lineside to cross off the numbers of passing steam engines in their ABC British Railways Locomotives (one pocket volume for each of BR’s four regions). By 1950 police were being called to exciting stations such as Preston to deal with the crush of spotters.

For most, the enthusiasm died out over time. The locospotters morphed into a railway preservation movement, rescuing dozens of branch lines and engines for posterity. One or two celebrity anoraks remain. Last year Sir Rod Stewart, 75, revealed to Railway Modeller (the magazine I once hid inside a copy of Vogue) a huge, intricate model of a US city he had built and donated $13,000 to restore a model railway in Market Deeping, Lincolnshire, that had been destroyed by vandals. Jools Holland and Neil Young are also fans.

“Our average customer is over 50 and we don’t think the average 50, 60 or 70-year-old is going to hop on a train to London anymore.”

For the most part, the transport fanatic is much maligned. My father has weathered our mockery with good-natured forbearance. When we made a Thomas the Tank Engine cake for my son’s birthday last year, my dad pointed out that Thomas is an E2 class locomotive and ours had too many biscuit wheels. Lately I have realized he is having the last laugh. Not only has his hobby relieved the stress of a high-pressure career and eased the shift to retirement. It is also now mitigating the boredom of being locked down. There is a poignancy to Ian Allan closing at a time when hobbies have never felt more important.

Nick Allan says the decision to close is commercial. Most specialist titles are now on Amazon and, while the magazine circulations drop, the chatter of excited hobbyists thrums on in online forums. In fact, the Internet seems to be taking the hobby in directions it has not been before. Vicki Pipe, best known as half of the YouTube sensation All the Stations — she and her partner, Geoff, spent 2017 visiting every railway station in Britain — said she was motivated partly by wanting to show that women have a role to play on the railways.

Nevertheless, when Ian Allan closes its doors later this month, a piece of British transport history will be lost forever. The customers in the shop last week had turned up despite Covid-19. People do not come here just to buy books, Foster said: “As you get older, your circle of friends gets smaller and it is nice to go somewhere where people know your name.”