I’m in Mellow Yellow, Amsterdam’s oldest coffeeshop. Beneath a thin veil of smoke, groups of men and women - young, old and of various nationalities - sit at wooden tables, chatting, joking and sharing spliffs. Reggae flows from nearby speakers, while a coffee machine noisily grinds beans behind the bar.

After finding fertile ground in a decidedly grey area of Dutch drug law, Mellow Yellow opened in 1967, blazing a trail for hundreds of other coffeeshops to follow.

Next year this historic establishment should be celebrating its 50th anniversary, but instead it will be pulling down the shutters for the final time: by order of the mayor, Mellow Yellow is to cease trading on January 1, 2017. This joint is going out.

Johnny Petram, owner of Mellow Yellow Credit: Gavin haines

“Mellow Yellow was the first coffeeshop in the world and now they want to close it,” says owner, Johnny Petram.

“I serve thousands of people every day; tourists and locals. I have Israelis and Palestinians in here smoking together. Even people who don’t smoke come here to have their photo taken. It’s part of the history of Amsterdam.”

But now Mellow Yellow looks set to be history as the mayor, Eberhard van der Laan, oversees the final phase of a government-backed programme to shut down any coffeeshop within 250m of a school. Mellow Yellow is one of 28 establishments to be affected by the initiative, which is allegedly aimed at deterring youngsters from taking up cannabis.

Mr Petram, 33, has hired a lawyer to help him fight the closure of Mellow Yellow. His main line of defence is that the nearby school is actually a hairdressing academy for fee-paying students, most of whom are 18 years old.

Cannabis for sale in an Amsterdam coffee shop Credit: alamy

“They are closing the world’s oldest coffeeshop because of a salon,” claims Mr Petram, whose personal future is at stake. “If we close on January 1, I will still have to pay €7,000 rent every month. How am I going to afford that if this place shuts? I don’t know what I’m going to do.”

Acting with unusual candour, the mayor’s office told Telegraph Travel that it doesn’t believe closing coffeeshops will stop young people from taking up cannabis.

The city hall council has pushed through a programme to "clean up" the red light district, forcing a further 22 coffeeshops to close

However, it is pushing the directive through as part of a deal with the national government that will exempt Amsterdam from enforcing the so-called Weed Pass, which prohibits non-Dutch nationals from visiting coffeeshops.

The Weed Pass has already been rolled out in other parts of the Netherlands, but Amsterdam has hitherto resisted the scheme, claiming it would lead to an explosion in street dealing.

“If we don’t strike a deal we would be forced to enforce the Weed Pass - and then we will have big problems,” says Jasper Karman, the mayor’s spokesperson, defending the recent closures.

Critics claim kowtowing to the government was a mistake: with an election looming next year, there is no guarantee a new administration would honour any agreements made with the previous government.

Detractors also claim the initiative, though touted as a nationwide scheme, specifically targetted Amsterdam.

“Other cities in Holland have already closed most of their coffeeshops, so this law doesn’t even affect them - it was aimed at Amsterdam,” says August de Loor, a government advisor and founder of the Bond Van Cannabis Detaillisten (BCD) union for coffeeshop owners. “The city has been tricked.”

There is one point that all sides can agree on: that half of Amsterdam’s coffeeshops have closed in the last two decades. Back in the Nineties there were as many as 350 of the cafes scattered around the city, today there are just 175.

Some have closed naturally, others have been forced to fold because their owners violated the strict rules governing coffeeshops. Most of the recent closures, however, are down to local policy; in addition to the “school rule”, the city hall council has also pushed through a programme to "clean up" the red light district, forcing a further 22 coffeeshops to close.

Most of the coffee shop closures are down to local policy Credit: JTB photo

“The council wants to increase the quality of the city centre, but only for rich people,” laments Mr de Loor. “I’m all for increasing the quality of the city centre, but not by kicking out coffeeshops.”

The local government made its case for gentrifying the red light district to Telegraph Travel.

“We had an enormous amount of coffeeshops, sex shops and brothels in the area and we wanted to make it more diverse and more attractive to a broader public,” says Mr Karman. “We wanted to create a better balance.”

Though considered a form of lowbrow entertainment by some, coffeeshops play a vital role in Dutch tourism: according to city hall figures, 25-30 per cent of tourists in Amsterdam visit a coffeeshop.

“Within five to ten years coffeeshops could be finished,” says Mr de Loor Credit: alamy

Coffeeshops are also part of the social fabric of Amsterdam.

“They are meeting points, like pubs; they bring people together and help keep the city cosy,” says Mr de Loor. “They are part of our culture, something unique to Holland.”

According to Mr de Loor, the closure of coffeeshops in Amsterdam is having an adverse effect on those that remain, as well as pushing more smokers onto the street.

“The coffeeshops that have survived are getting busier and they are kicking out the chairs - kicking out the social part of the coffeeshop - to essentially become cannabis supermarkets,” he said. “You go in, buy your weed and f*** off. That’s a terrible development.”

Perhaps the biggest concern for Amsterdam’s coffeeshops, however, is the threat of a new national government. After Brexit and Trump, locals are increasingly fearful that a right-wing party could prevail at next year’s elections, thus spelling the end of coffeeshops as we know them.

“Within five to ten years coffeeshops could be finished,” says Mr de Loor. “That’s my most negative scenario.”

#Amsterdam has lost roughly half its coffeeshops in just two decades. A photo posted by Gavin Haines (@gavin_haines) on Dec 4, 2016 at 11:44pm PST

City hall says it has no plans to close any more coffeeshops in Amsterdam; it even moots the idea of opening others in the future, assuming the government doesn’t impose further restrictions.

That’s scant consolation for Mr Petram and his customers. Unless city hall changes its mind soon, Mellow Yellow will slide into the history books.

“There are other coffeeshops, but they don’t have the same atmosphere,” says Rasta, a regular at Mellow Yellow. “I don’t know where I’d go if this place closed.”