On a hilltop in central Corfu, a marble bust carved in the classical style gazes skyward, lean, fine-featured and composed to the point of austerity. There is no uniform, no decorations, nor symbols of office, just a name cut into the base in Greek capitals: Ι Α ΚΑΠΟΔΙΣΤΡΙΑΣ. The bust stands alone in the gardens of Koukouritsa, once the family home of Ioannis Kapodistrias, the first governor of Greece. The villa is now the only museum in the country dedicated to the man who gave up one of the most powerful diplomatic positions in Europe to return to a country that was barely a country and try to build one.

Without Kapodistrias, there may have been no modern Greek state, and the map of Europe might look very different today. He spent years supplying material and moral support to the Greek revolutionaries; once independence was won from the Ottoman Empire, he negotiated directly with Britain, France and Russia over the new country’s borders and future, then set about building the institutions, its currency, courts, schools and civil service that the modern state still stands on. “He who murdered Kapodistrias murdered his homeland,” Swiss philhellene Jean-Gabriel Eynard wrote on hearing of the statesman’s assassination in 1831 at the hands of rebel leader allies turned enemies.

Yet 250 years after his birth, Kapodistrias remains one of the least well-known politicians of post-Napoleonic Europe outside Greece, and often within it. Even the museum that preserves his memory is struggling “to cover basic operational needs,” as its director recently told Greek newspaper Kathimerini. A new film about his life, opening in UK cinemas this week after a successful run in Greece and screenings across Europe, is attempting to change that.

Born in Corfu in 1776, when the island still belonged to Venice, Kapodistrias entered the Russian diplomatic service in his late 20s and, within six years, rose to become joint foreign minister of the Russian Empire under tsar Alexander I. At the Russian court, he moved in a glittering cultural circle. “He was a political operator of great skill,” says Roderick Beaton, author of Greece: Biography of a Modern Nation. “Foreign politicians and diplomats at the time, particularly of the Vienna Congress, thought highly of him.”

The film, Kapodistrias, written and directed by Yannis Smaragdis, makes sure to show that while its protagonist was shaped by Russia, he was not subservient to it. In one scene, Kapodistrias urges the tsar towards war with the Ottomans, calculating that a Russian front would draw Ottoman forces away from Greece.

On his promotion to foreign minister, Kapodistrias warns the tsar that if it ever came to a choice between Russia and Greece, he would choose Greece. Not long after the revolution, Kapodistrias resigned from St Petersburg and spent years working the diplomatic circuits of Europe on behalf of his homeland. He later reflects on what kept him alive during his years in Russia: the knowledge that a grave was waiting for him in Corfu, “a grave”, he says, he “never once thought to trade for the largest palace in the world”.

Yet when the first emissary from the independence movement came to him, Kapodistrias is said to have turned them away. Things changed when he was elected Greece’s first head of state in 1827: he arrived the following year to a country with no currency, no functioning courts, no schools, and no army answerable to any single authority.

Kapodistrias is said to have worked from five in the morning until late at night, and the film portrays him as constantly working, attending mass and revered by those around him. He famously insisted: “First we must make Hellenes, and then make Hellas,” recognising that building a nation required first building its people. He founded schools, minted Greece’s first currency, the Phoenix, organised the judiciary, and introduced the potato to stave off famine.

There are limits to how modern a figure Kapodistrias can be made to seem, however. Smaragdis’s film strains to build a colourful character out of his relationship with Greek aristocrat Roxandra Sturdza, which may have been less romantic in real life, and his association with bohemian types like the writer Alexander Pushkin, on whose behalf Kapodistrias intervened when the tsar exiled him over a politically offensive poem.

“The fact that he was a friend of Pushkin means he must have been an interesting person rather than a boring back-office swot,” says Jonathon Bond, a British researcher who has spent years studying Kapodistrias.

There’s little the film can do about Kapodistrias’s politics, which historians agree leaned towards the sort of autocracy that he had been used to in Russia. Some accused him of being a tyrant motivated by selfish ambition; others call him an enlightened despot, a description Beaton finds not far from the mark.

“The Greeks wanted colourful heroes after the war of independence, and he doesn’t provide that,” Bond says. “And if you’re a monarchist, he’s a failed republican.” He didn’t raise a sword in the war of independence, and worse still, he tried to cramp the style of the colourful warlords who had. “He was a sort of backroom diplomat of a type they didn’t really recognise.”

This tension is shown vividly in the film; there is no warmth between the austere statesman in his black European coat and the colourful, gun-wielding men around him.

Addressing the warring local leaders directly, Kapodistrias tells them Greece is at war with the Ottomans, and they must contribute. “We have to give?” one questions. “Weren’t the Ottomans your enemies?” Kapodistrias asks. “You’re an enemy too,” comes the answer. “Beware”.

Lead actor Antonis Myriagos describes his approach to the role as “the chronicle of a death foretold”. When he is warned of an attempt on his life, he goes anyway. As he walks to the church of St Spyridon in Nafplio, where the murder takes place, he is followed by what appears to be a chorus of mourning women, in the tradition of a Greek tragedy.

That Kapodistrias remains largely forgotten outside Greece can be explained “only very partly” by his assassination, says Beaton. More likely is that he was “highly controversial and divisive in his lifetime, and, more remarkably, still is.” Beaton adds: “In more recent times he has been adopted as a hero by the political right, and condemned as a dictator by the left.”

In Greece, where the film opened on Christmas Day, critics and the public were sharply divided. Professional reviewers were largely withering; audiences embraced it, while it has now been confirmed as the fifth highest-grossing Greek film of all time. The gap between the two verdicts is itself a Kapodistrias story; a figure who still, nearly two centuries on, provokes argument about what Greece is and what it should have been. “His is a fascinating story,” says Beaton, “and deserves to be much better known.”