Here’s a question for your next pub quiz: Who is Europe’s longest serving leader?

Russia’s Vladimir Putin, Belarus’ Alexander Lukashenko and Turkey’s Recep Tayyip Erdoğan are all likely to be popular guesses. But the dubious honor belongs to Milo Ðukanović, the president of Montenegro.

Milo, as he is known in the region, has been calling the shots in the tiny Adriatic state for almost 30 years — as president, prime minister or party leader, thanks to the occasional Putin-style switch between posts. And at 59, he could well have another decade or two in the tank and still overtake records set by Africa’s longest-lasting despots.

Or at least it seemed that way until quite recently. These days, Ðukanović’s grip on power looks considerably less firm.

Some 10,000 people — a not insignificant number, when you consider Montenegro’s population is only 630,000 — flooded the capital, Podgorica, last weekend to protest his government and call for his resignation. A stormy debate in the country’s parliament also saw calls for Ðukanović to step down.

The trouble started when Milo fell out with prominent Montenegrin businessman Duško Knežević. In December, authorities accused Knežević of a series of misdemeanors and seized his assets. The trouble was that Knežević — who owns Atlas Group, a conglomerate of banking, insurance and health interests — is not just any businessman. For the past 25 years, he has been closely involved in the government’s most intimate affairs and knows, figuratively if not literally, where the bodies are buried.

Knežević didn’t take well to the scrutiny, and responded to the allegations by launching a blistering campaign against Ðukanović and his family from London. In a succession of social media posts, he released information on a series of buried corruption and misgovernance scandals that go up to the highest levels of Montenegro’s ruling class.

In one of the most damaging revelations, a senior member of Milo’s party is apparently caught on camera accepting an illegal cash donation from Knežević. The businessman also alleged Ðukanović is the owner of a vast oligarch-kitsch villa valued at $10 million. (Ðukanović has denied Knežević's allegations.)

The string of unsavory revelations risk prompting those within Ðukanović’s party who believe a change in leadership is overdue to join up with the opposition and force him to retire.

For all his qualities and achievements, Ðukanović now belongs to the past.

After I first met Ðukanović in the mid-1990s, when I was ambassador in Belgrade, I remember reporting back to London that he was different from most other former Yugoslav leaders. He was from a different generation to the likes of former Serbian President Slobodan Milošević, of course. But he also struck me as more moderate, more reasonable, and very concerned about putting the interests of Montenegro first. This was someone we should try to do business with, I told London.

Over the years, Ðukanović seemed to fulfill that promise. In the lead-up to the Kosovo war, he disowned Milošević and the policies of the Belgrade government and managed to ensure that Montenegro was scarcely targeted in the NATO bombing campaign. He also showed personal courage and real political dexterity in the aftermath, guiding his country to independence from Serbia and then, in the face of huge hostility from Moscow, to membership of NATO.

Putin’s response was to send his bungling GRU officers to Montenegro to try to organize a coup against Ðukanović — a task they carried out as effectively as their attempted assassination of Sergei Skripal in Salisbury.

But for all his qualities and achievements, Ðukanović now belongs to the past.

He links Montenegro to the era of former Croatian President Franjo Tuđman and Milošević — not to mention former U.K. Prime Minister John Major, ex-Russian President Boris Yeltsin and former U.S. President Bill Clinton — of communist Yugoslavia, wars in Bosnia, Croatia and Kosovo, and allegations of cigarette smuggling and narcotics trafficking.

The epoch of Balkans politics in which his career was forged was one of strong men, of opacity, rule-bending and a lack of accountability. But if Montenegro is ever to achieve full membership of the European Union, it will need a different kind of leader and a different political culture.

The EU accession process demands that applicant states reach tough standards of propriety and the rule of law, adhere to regulations and get tough on corruption. Montenegro has a long way to go to combat criminality and develop a culture of transparency and accountability. And it will need a leader who is capable of leading on these issues, not one whose own integrity is under question.

The good news is that Montenegro already has those leaders: The current prime minister, Duško Marković, for example, is a calm and effective presence at the head of the government and his predecessor, Igor Luksić, is a bright star of the next generation.

The transformation of North Macedonia, another former constituent republic of Yugoslavia, over the past 18 months is a prime example of how a change of leadership can transform a country’s image and help along the process of its accession to the EU.

The country’s new liberal prime minister, Zoran Zaev, moved quickly to mend relations with the Albanian community and break a 25-year deadlock with Greece on his country’s name. By doing so, he’s put his country on a fast track to NATO and smoothed its path to membership of the EU.

Montenegro should be setting itself up for similar success. It’s as good time as any to say hvala i zbogom — thanks, and farewell — to Milo Ðukanović.

Ivor Roberts is a former British ambassador to Yugoslavia, Ireland and Italy and was president of Trinity College, Oxford from 2006 to 2017.

This article has been updated to correct the surname of the Montenegrin prime minister.