Few cities have had heroin quite so in their faces as Zurich.

The Swiss financial capital - one of Europe's wealthiest corners - for years had a booming market for the drug right in its heart.

Platzspitz - a green slither of land pointing in to the middle of the Limmat river - is now a popular family meeting place.

Until 1992 it was the Needle Park, a no-go area where police effectively turned a blind-eye to drug use in they hope it would be contained.

The tactic did not work. Platzspitz became a hub of criminality and was eventually closed down. But at least it meant that heroin - unlike in so many other parts of Europe - was not hidden from view.

Two years later Switzerland tried another experiment with heroin. It started using public money to treat addicts with the drug.

Two decades on, this is now seen as best practice for the most vulnerable users, the old and infirm who can't be stabilised any other way.

The scheme has been so successful that many Swiss wrongly think the country has fixed drugs. Crime is down, begging too. The social costs of addiction have faded from memory. But it is simply that drugs users aren't as visible as they were - or as dangerous or endangered.

Psychiatrist Thilo Beck, of Zurich's Arun Centre for Addiction Medicine, said: "It's as if people think there isn't a problem any more.

"There are consumption rooms where users take their drugs and the drugs are provided by doctors. So people don't see anything in public. But the consumption rooms and the system still costs money. The Needle Park has gone; it's for families now."

This success has brought an issue Scottish drugs workers can only dream of: voters and politicians think they don't need HAT and other services any more because they don't see public chaotic drug user.

The Swiss - in one of their many referendums - voted on HAT in 2009.

The populist right had argued - with rhetoric borrowed from America's war on drugs - that HAT would encourage people to take drugs.

The Swiss were not convinced. Nearly two-thirds of the population backed the scheme. Similar initiatives are now underway across Europe - although no-one in Scotland has ever applied for a licence to treat patients with medical heroin and the governments remains ethically opposed to consumption rooms.