Asked by the Observer to explain the issues he has with his morning rail service, Croydon commuter Ian Devlin needs one clarification: “How many pages do you have?”

“It’s a disgusting,” he says, waiting on South Croydon’s platform three just before 8am, with no expectation that he will have a seat on his journey. “Cancellations, reduced carriages – I won’t get a seat on this one, either. I think they should be brought back in [to national ownership].” Steve Shelts, an accountant, says that the service is bad, but counts himself lucky. He says his counterparts at the next stop, East Croydon, have “no chance” of a seat and face a battle to board.

Sure enough, on this Friday morning, trains arriving at East Croydon are packed and behind schedule. “I’ve stopped caring about a seat. I think nationalisation could be the answer,” says Tony Molloy, a housing manager.

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The frustration is unsurprising. The Southern service from East Grinstead to London Bridge, which arrives at Croydon stations around 8am, was recently deemed the most overcrowded in Britain. And on top of fare increases last week, passengers on the route will be among thousands across Britain facing the effects of strike action, with walkouts planned on six different lines. With such misery, and unions claiming that rail companies are putting profits before services, it is little wonder that some passengers support the radical solution now being put forward by Jeremy Corbyn’s Labour – a return to a nationalised rail service.

Other factors have fuelled a renewed debate over who should run Britain’s trains. The government’s decision to allow Virgin and Stagecoach to end their joint venture running the East Coast main line three years early, after claims they had lost more than £100m, has led to accusations that private companies can just hand the keys back whenever profits dry up. Meanwhile, the huge growth in passenger numbers since privatisation, a fact repeatedly used to kill off talk of nationalisation, may have come to an end.

Recent figures have showed that the number of rail passenger journeys in Britain fell last spring after two decades of almost constant growth since the end of British Rail. Journeys fell by 2.7% against the same period in 2016.

Ed Miliband, the former Labour leader, says the time for the public sector to step in has arrived. “Experience clearly shows that the franchise system is broken – it ends up being a system that privatises the gains and nationalises the losses,” he says. “Companies have an incentive to say up front: ‘We’ll give you all this money,’ and then pull out. The supposed gains of competition are massively outweighed by the costs, problems and inefficiencies.”

One of the absurdities of the current system, Miliband says, is that a raft of foreign state operators in Germany, Italy, France and elsewhere are the ultimate owners of several companies running railways in Britain. “The great irony of the system seems to be that you can have any state operator you like as long as it isn’t British,” he says.

Meanwhile, Ian Taylor, a rail consultant drafted in by Labour to design its rail policy, says public ownership would tackle so-called fragmentation – where one body, National Rail, owns the infrastructure, and a patchwork of private franchises runs train routes, causing complicated ticketing, issues over coordination and waste.

Commuters standing on a train into central London. Photograph: Daniel Leal-Olivas/AFP/Getty Images

So is it time for a radical rethink? Certainly, says Anthony Smith, chief executive of independent watchdog Transport Focus, the policy by successive governments to shift the burden of paying for the railways from the taxpayer to the farepayer should now be ended. “Over a decade, it has reversed from 70:30 to 30:70, with passengers paying more,” he said. “I think that policy has now hit the buffers. I don’t think you can extract much more from passengers in annual increases.”

Christian Wolmar, the rail expert and Labour supporter, adds: “The more they push the fares up, they are in danger of killing the golden goose.”

Some of those who support a privatised system agree that increases may not be sustainable. Julian Glover, a former special adviser at the Department for Transport, says there is a business case for freezing fares. “The 3.4% increase this year is a mistake. I think it will suppress demand and create less revenue. That figure is big enough to stop people from travelling, and we’re seeing some of that now.”

However, critics of Labour’s plan claim the party’s critique misrepresents the way Britain’s railways are run. Far from profiteering, they say, the relatively low profits and major political interference have seen a lack of bidders for rail franchises – with some providers like National Express exiting the market altogether.

“Profits are about 3.4% across the industry,” says Mark Smith, a former government official once in charge of regulating fares and ticketing. “So if you eliminated all profits overnight you would get a one-off 3.4% cut in fares, which isn’t going to set the world on fire.”

Others point out that many lines, such as those run by Chiltern or C2C, have been transformed by private owners and perform well. Overall, the industry says that the private railways have been a success story, more than doubling passengers. “In the next 18 months alone, customers and communities across the country will see a transformation in the railway, with 5,700 new carriages, 6,400 more services a week and 180 stations improved,” says Paul Plummer, chief executive of the Rail Delivery Group, which represents the rail industry.

Jeremy Corbyn’s Labour party is seeking to renationalise Britain’s railways. Photograph: Aaron Chown/PA

A quick trip on the East Coast main line from London to York shows that while the line’s ownership has been a source of controversy, it does not have the practical problems of Croydon’s commuter trains. Friday’s lunchtime service reached York in under two hours, with no delays and with spare seats. Industry insiders say that the failure of the East Coast franchise was down to the fact that promised line upgrades were delayed – meaning Virgin and Stagecoach were not getting the line they had been promised.

And not all agree that fragmentation caused by privatisation is an impossible problem. “Look at Heathrow,” says Nigel Harris, the editor of Rail magazine. “Your flight is delivered by far more companies than those that handle the railways – ground handlers, caterers, airline, airport. Yet it works.”

While disagreements over ownership rage, there is more agreement that, at the very least, the franchise system needs reform to stop companies making unrealistically high bids to win the right to run services. One former government official said the DfT had to take some responsibility for accepting bids it knew were risky.

There is also growing support for some kind of organisation to make sure that the rail companies and public bodies work together. “Passengers want to know who is in charge of their service,” says Anthony Smith. “Who is accountable? I’m not sure that many passengers care whether it is public or private. They want it to be good value, on time and with someone accountable for it. That’s the bit that is missing.” Glover adds: “What people in the industry talk about is a guiding mind – a system operator – which is quite boring, but exactly what is needed. It doesn’t have to be wholly private or state-run.”

There are other points of agreement. Figures on both sides of the nationalisation debate hail the successes of devolving train services – pointing to Transport for London’s smart ticketing and the record of Mersey Rail and London Overground. “Mersey Rail was known as Misery Rail,” says Stephen Joseph, executive director of Campaign for Better Transport. “The North London line was a byword for crime and horror. Then they got taken over by the local authorities who basically cared whether anybody used them and what kind of service they got. There’s a big argument floating about devolution about this.”

But where does all that leave our poor Croydon commuters? The aim for those travellers, says Glover, should be to win a decent slice of the upcoming £50bn pot earmarked for rail investment. Another alternative, suggested by Miliband, would be to hand their service to TfL.

At the National Rail Museum in York, just a short walk from the city’s East Coast line station, an exhibition on British Rail reveals that today’s arguments around nationalisation are simply the latest skirmish in a long-running battle. On the eve of British Rail’s demise, the Daily Telegraph, hardly a cheerleader for state ownership, ran a front page poll showing that “71% of rail users oppose privatisation”.

Dig deeper and it becomes clear that the frustrations felt in Croydon have an even longer vintage. As economist Ernest Foxwell noted in 83 (1883): “The great blots on the South Eastern are its unpunctuality, its fares, [and] its third-class carriages.”