There isn’t a lot to recommend Leipheim. A small town of about 7,000 inhabitants, it sits about halfway between Munich and Stuttgart on the border shared by Germany’s two southernmost states, Bavaria and Baden-Württemberg. The train from Munich passes through pleasant-enough countryside on its way here before it pulls into Leipheim station but the town itself is neither that pretty nor historic. And this particular morning it’s draped in thick fog and eerily quiet.

Nonetheless, Leipheim regularly welcomes visitors from all over the world. Why? A clue is instantly visible across the road from the station: two banners hanging either side of the entrance to a factory with the same single word emblazoned on them: Wanzl. This company, which is headquartered in town and employs more than 2,000 people from the area, is a draw for businesspeople in the retail sector. For them, Leipheim means just one thing: shopping trolleys.

There is something of the provincial theme park about Wanzl HQ, two minutes up the road from the station. Before entering the building, visitors are greeted by a metal sculpture of the world. Sitting atop it, with its course set for the North Pole, is a shopping trolley, the item that Wanzl builds more of than any other company on the planet. Everyday objects here have been redesigned to resemble the company’s flagship product: the seats around an outdoor pond, the chairs in a meeting room and even the desktop pen pots.

Wanzl’s speciality is almost anything that can be pushed along on wheels. Here in Leipheim, and at nine other plants worldwide, the company manufactures chambermaid carts for the hotel and cruise industries, luggage trolleys and mobile newspaper racks for airports and hotels, and wire cages on wheels for logistics and e-commerce businesses. It has also moved into other fields, including retail design and shop-fitting and, most recently, security gates for buildings and airports. But still about 40 per cent of its business is in manufacturing the globally ubiquitous, and eminently prosaic, shopping trolley.

If you have ever collected one of these from a bay and steered it through a supermarket, the likelihood is that you’ve come into contact with a Wanzl product. “I think there is no country in the world that we have not supplied with shopping baskets, trolleys or whatever,” says Bernhard Renzhofer, Wanzl’s chief sales officer.

To trace the evolution of Wanzl is to trace the evolution of modern retail. The company was established in 1947 by Rudolf Wanzl, who had previously run his own metalworking company in Giebau in the Sudetenland (now Jivova in the Czech Republic) but who had been forced to flee at the end of the Second World War when the Red Army tore through the area. In Bavaria the three-person company started again with a new product: a small handheld wire shopping basket.

This single product, now quite banal, represented a profound societal shift in postwar Germany and across the West. It marked the birth of Selbstbedienung, or self-service. Previously shoppers would go to a grocer’s and an assistant behind the counter would fill a bag for them; from this point onwards, however, they were on their own (until the till, of course), selecting their own groceries.

The latter half of the 20th century was the heyday of the large-format suburban supermarket, aided by the rapid rise of the car. Wanzl was there to capitalise on the shift by making a simple trolley on wheels to carry two baskets stacked one on top of each other and then, in 1950, a shopping cart closely resembling the models we see today. “The company maybe had 20 employees at the start of the 1950s; that number was probably over 100 by the end of the decade,” says Gottfried Wanzl, Rudolf’s grandson and chairman of the company’s board. Born in 1954, he remembers when he was a boy playing table tennis with the factory workers.

Since the 1950s, Wanzl has conquered the globe. Today it is the world’s biggest maker of shopping trolleys by some margin: its 4,900 employees across 13 production sites churn out 2.5 million of them a year. It has subsidiaries in 27 countries and sales offices in 50 others, and in 2017 it expects a turnover of about €700m. Its customers – supermarkets and similar retailers – include virtually all of the well-known brands, including Sweden’s Ikea, Germany’s Lidl and the UK’s Tesco. When it acquired Technibilt in 2012 it gained dominance in the US market too.

Although Wanzl has manufacturing facilities round the world, roughly half of the company’s trolleys are still produced in Leipheim (and some in nearby town Kirchheim) across four vast buildings. It’s a peaceful morning in Leipheim – until the door to Factory 4 is opened and the air is filled with the incessant whirr of machines and the smell of smouldering metal. Inside, Wafios r23 machines take huge rolls of steel wire and cut them into straight rods. Then state-of-the-art Kuka robots work with factory staff to fuse the rods into the classic shape of a trolley basket. These are then galvanised with zinc, powder-coated and fastened to a “chassis” before the wheels are screwed on at the end of the process.

Virtually every part of the shopping trolley is made in-house, including the wheels (which themselves comprise up to 40 separate parts). “The company started as a small workshop doing everything, so even when it grew into a big factory it still had to do everything,” says Dennis Witzing from the marketing team, as he leads us through the hall where completed trolleys are stacked up waiting to be sent out to retailers. There are about 5,000 ready to roll today. “That’s not even that many,” says Christian Remmele, the 31-year-old head of dispatching. “On a busy day we’ll send out around 8,000. If we’re doing 35,000 in a week then we know it’s busy.”

The manufacturing process is highly efficient and hi-tech yet the end product itself is still relatively simple. Granted, Wanzl’s most recently launched trolleys – the Salsa and Tango models – are made elsewhere before being assembled here. But even so, the average shopping trolley today is not that dissimilar to those of the 1950s, which are on display in Wanzl’s sales building.

That is about to change, however. If the second half of the 20th century saw a huge shift in the way we shop then the start of this century will witness similar upheaval. As one of the biggest b2b players in retail, Wanzl is having to adapt at breakneck speed. “I think if we did nothing and continued as we are we would no longer be successful after three years or so,” says Renzhofer.

One of the biggest trends that his company is having to grapple with is the move away from big out-of-town supermarkets towards smaller-footprint shops, as shoppers increasingly opt for regular small trips instead of the one big weekly effort. “We’re seeing stagnation for the bigger trolleys and stronger growth for smaller ones,” says Renzhofer. “Definitely that’s the trend. Quite simple.” This is also visible in Wanzl’s shop-fitting business, where retailers are increasingly seeking out smaller and more flexible shelving and product-display units for their more compact shops.

The particularly challenging trend is the digitalisation of retail, as more and more customers migrate online. Luckily Wanzl is well placed to handle this and, because it counts e-commerce players such as Amazon and Zalando among the customers of its logistics unit, it is in the solid position of benefitting when online retail does well. Above all though, Wanzl is making sure it remains an indispensable part of offline retail in order to safeguard the future of the trolley. Part of this is messaging. As Jürgen Frank, head of marketing and product management, neatly puts it: “The trolley is the one employee who stays with your customer from the start to the end of their shopping trip.”

Wanzl has also tasked itself with coming up with a vision for what offline retail will look like in years to come. Down in the belly of Wanzl’s Leipheim sales centre, we get a glimpse of this vision.

Here it has built a life-size grocery store – complete with shelves laden with Wanzl-branded products – to demonstrate its latest innovation: Wanzl Connect.

Launched at this year’s EuroShop trade fair, Wanzl Connect is a system that offers offline retailers a way into the information age; one component is a set of new “smart” trolleys that can be tracked in a shop. The data collected could tell the shop manager, for instance, how long people take to move around and where they linger longest.

The second key component of Wanzl Connect is a smartphone app, which customers can use to keep their shopping list, scan items in-store and pay contactlessly at the end of their trip. Again, data is important. With the help of “beacons” (Bluetooth transmitting devices) placed strategically around the shop, customers can be notified on their phones of deals and special offers relevant to them.

“This is the last chance for physical retail to compete with online retail,” says Andreas Starzmann, director of Wanzl’s digital office. “You can’t compete on price or convenience so it will have to be about the experience. And to create a good experience you need to know as much as possible about the customer.” He’s quick to point out, however, that Wanzl itself won’t hold customers’ data: for now it will simply build the “architecture” for retailers to access the information. That said, Starzmann can see Wanzl becoming a data-driven firm in the future.

In 2018 the company will go one step further by launching a “checkout trolley”, as Renzhofer calls it, with a product scanner and digital display built in to allow customers to pay using their trolley and not at the checkout. “We are convinced that in the near future, for at least some part of the day, we will have supermarkets where the complete process of a customer coming in, getting out and paying is done without staff,” says Renzhofer.

But is this what customers want? Supermarkets empty of staff and full of transmitters firing notifications of offers to their smartphones? It sounds miserable. Frank is quick to reassure. “I think we will see both,” he says. “On the one hand a fast and convenient way of shopping; on the other, much more ‘experience’ during the process than today.” What’s clear is that whichever way retail turns next, Wanzl will be there to roll with it.

The shopping trolley means much more than just an hour lost in an overlit retail barn. Next time you’re in your local Costco, Migros or Waitrose, take a look at your four-wheeled friend and tell me you don’t see a modern metaphor, a cultural signifier, a film star.

Culturally, the shopping trolley came of age in 1965’s The Ipcress File. Michael Caine’s Harry Palmer is a savvy working-class spy who knows his way round both the kitchen and the bedroom, a direct counter to James Bond’s upperclass black-tie lothario. The best scene is set – oh yes – in a newly inaugurated Safeway. Inside the supermarket, Palmer’s old boss Colonel Ross clumsily stage-manages an “accidental” meeting among the tinned champignons and Vesta chicken curry to recruit Palmer to spy on his new boss. The script is tight and the performances spotless but the crowning glory is a trolley duel fought in the aisles. Palmer is insouciant at the controls of his trolley; Ross, a relic.

Ipcress was a kitchen-sink spy film that displayed espionage’s sometime seedy reality and, ever since, shopping trolleys have been used to imbue their pushers with an aura of deep reality, no matter who they are. The Duchess of Cambridge has been photographed doing a dash round Waitrose (she’s not too posh to push a trolley); Theresa May went there too (a trip to Tesco would have seemed disingenuous), the day after that bloody awful snap election and Colleen Rooney, wife of Wayne, goes to m&s Food to “virtue signal” and take her mind off the infidelity. The all-important “trolley shot” signifies dignity, ordinariness, approachability and a certain self-made streetness. Capable, electable and, you know, just like you.

Of course there are also a whole other load of films of the Jackass variety that have made racing shopping trolleys down mountains, across eight-lane highways and off waterfalls seem real. But those idiots aren’t asking you to vote for them. Are they?