One month after the French channel port of Dunkirk introduced free public transport for all, a small revolution is taking place.

Two women, perfect strangers until now, are chatting across the aisle about nothing in particular. One admits she sometimes takes the bus “just for the fun of it”. A young man wearing headphones is charging his mobile in a socket just above the “request stop” button.

On another bus, Claude Pointart, 65, who is retired, says free buses mean her pension goes further. “I’m saving money and they come every 10 minutes so I don’t have to wait long. But there’s a lot more people taking the bus so you have to avoid the rush hour if you want to sit. Still, I think it’s a good thing.”

On a city bus making its way around the historic port city, passengers smile at the driver and say “Bonjour” as they board. Some of the city’s fleet of new buses, painted in dazzling colours – pink, orange, green, yellow and blue, with upholstery to match – have wifi.

The urban authorities have plans for debates, music and possibly the occasional celebrity on board. A “Sport-Bus” with an interactive game, quiz screen and a selfie camera is already in operation.

Georges Contamin, 51, says he has reconsidered how he travels about the city since the buses became fare-free. “Before, I almost never took the bus, but the fact they are now free as well as the increase in the cost of car fuel has made me reflect on how I get about,” Contamin says.

At the bus stop opposite the port, even the persistent drizzle and howling wind rocking the boats cannot dampen Marie’s enthusiasm. “I never used the bus before,” she says. “It was too much bother getting tickets or a pass. Now I leave the car at home and take the bus to and from work. It’s so easy.”

One month ago, Dunkirk – with a metropolitan population of 200,000 – became the largest city in Europe to offer free public transport. There are no trams, trolleybuses or local commuter trains, but the hop-on-hop-off buses are accessible and free – requiring no tickets, passes or cards – for all passengers, even visitors .

The scheme took its inspiration from Tallinn in Estonia, which in 2013 became the first European capital to offer a fare-free service on buses, trams and trolleybuses, but only to residents who are registered with the municipality.

They pay €2 for a “green card”, after which all journeys are free. The city has reported an increase of 25,000 in the number of registered residents – the number previously stood at 416,000 – for which the local authorities receives €1,000 of each resident’s income tax every year.

Free urban transport is spreading. In his research Wojciech Keblowski, an expert on urban research at Brussels Free University, says that in 2017 there were 99 fare-free public transport networks around the world: 57 in Europe, 27 in North America, 11 in South America, 3 in China and two in Australia (Central part of Melbourne has free trams, and the central part of Perth has free buses).

Many are smaller than Dunkirk and offer free transit limited to certain times, routes and people.

In February this year, Germany announced it was planning to trial free public transport in five cities – including the former capital Bonn and industrial cities Essen and Mannheim. In June this was downgraded to a slashing of public transport fares to persuade people to ditch cars.

The largest in the world is in Changning , in China’s Hunan province, where free transit has been in operation since 2008. Passenger numbers reportedly jumped by 60% on the day it was introduced.

A study into free public transport by online journal Metropolitics found an increase in mobility among older and younger people, and an increased sense of freedom.

One month on, the Dunkirk mayor, Patrice Vergriete, who promised free public transport in his 2014 election campaign, says the project has been an overwhelming success, with a 50% increase in passenger numbers on some routes, and up to 85% on others.

Who needs extra car parking?

Sitting in his large office under a poster of Nelson Mandela, Vergriete claims it is a win-win measure for his home city, where previously 65% of trips were made by car, 5% by bus and 1% by bicycle. The other 29% walked.

“The subject of free public transport is full of dogma and prejudice and not much research. This dogma suggests that if something is free it has no value. We hear this all the time in France,” he says