(CNN) When Boris Johnson finally announced he would step down as UK Prime Minister on Thursday, after desperately trying to cling onto power despite a historic government rebellion, his decision sparked a sense of relief across Westminster.
In Kyiv, it was met with despair.
Johnson has been one of the most vocal supporters of Ukraine as it tries to defend itself against Russia's unprovoked assault, and his departure stirred up fears that the UK's support for the country -- worth £3.8 billion ($4.6 billion) so far this year -- might start to dwindle.
With the whole Western world united behind it, Ukraine has no shortage of supporters. But Johnson was seen as a special ally in Kyiv. In early April, he became one of the first foreign leaders to make the precarious trip to the Ukrainian capital, then returned on another surprise visit last month.
Johnson has forged a close relationship with Ukrainian President Volodymyr Zelensky, who said he was sad to see him leave.
"We all heard this news with sadness. Not only me, but also the entire Ukrainian society," Zelensky told Johnson in a phone call on Thursday, according to his office. "We have no doubt that Great Britain's support will be preserved, but your personal leadership and charisma made it special," Zelensky added.
Kristine Berzina, senior security and defense policy fellow at the German Marshall Fund of the United States, said that as well as the UK's military support, Johnson's personality has played a big role in the way Ukrainians see him.
"The loudness and brashness of Johnson's support for Ukraine's fight ... stands in stark contrast to the understated support given by Germany's Chancellor (Olaf) Scholz. Here was a leader of a major European power, a nuclear power, not afraid to back Ukraine and call Russia out," she told CNN in an email.
While French President Emmanuel Macron has faced criticism from Zelensky, who has accused him of trying to appease Russian President Vladimir Putin, Johnson was always viewed as an unequivocal supporter.
The outgoing British prime minister is so popular in Ukraine that several towns have already proposed naming streets after him. When the news of his resignation broke, the leading supermarket chain Silpo added an illustration of Johnson's trademark mop of messy blond hair to its logo.
Ukrainian presidential adviser Mykhailo Podolyak called Johnson "a hero," while Foreign Minister Dmytro Kuleba said the British leader was "a man of no fear, ready to take risks for the cause he believes in."
Peter Kellner, a British polling expert, journalist and visiting scholar at Carnegie Europe, said Johnson's dedication to Ukraine was likely inspired by history -- and his own political needs.
"Ukraine has given Johnson a rare chance to emulate his hero: to take a tough and uncompromising stance on an issue that is both moral and military," he told CNN in an email, referring to Johnson's well known admiration for Britain's World War Two leader Winston Churchill. Kellner added that Johnson often tried to turn attention to Ukraine at time of crises at home.
"The Russian invasion came at a time when Johnson was engulfed by scandal, notably over 'Partygate', and was also afflicted by the political costs of rapidly rising inflation," he noted. "He is not the first, and won't be the last, national leader to use toughness abroad to disguise weakness at home."
Glyn Morgan, associate professor of political science at Syracuse University, also questioned Johnson's motivations.
"If one were cynical, one might think that Johnson's commitment to Ukraine reflected a shameless effort to distract attention from his longstanding relationships with Russian business interests and his crumbling popularity in the UK at the time," he said.
"If one were romantic, one might think that Johnson's commitment to Ukraine reflected a very British fondness for the underdog, the plucky hero standing against the larger bully. Johnson is nothing if not a romantic, who sees himself as the hero in an epic."
Johnson has championed Ukraine, but Britain's commitment to help it face down Russia started way before he came to power -- when Russia illegally annexed Crimea in 2014.
In 2015, the UK military launched Operation Orbital, which was aimed at providing the Ukrainian armed forces with guidance and training.
That relationship grew even deeper in 2016, when the two countries signed a 15-year defense cooperation agreement that focused on more training and intelligence sharing.
Still, at that time, the UK was reluctant to provide Ukraine with arms, fearing any supplies of lethal weapons would escalate the conflict and anger Russia.
That changed late last year, when Russian President Vladimir Putin started amassing troops on Ukraine's border.
In January, under Johnson's direction, the UK government shipped its first batch of weapons to Ukraine -- 2,000 anti-tank missiles. Since then a steady supply of weapons and ammunition has followed.
According to a British government statement, the UK has announced £2.3 billion ($2.77 billion) worth of military support for Ukraine since the outbreak of the war in late February -- more than any other country except for the United States.
This kind of help is unlikely to stop with Johnson's exit.
"The support for Ukraine is shared across the British political spectrum -- left and right, political classes and the military-administrative classes... his departure will have no impact, other than that his successor will not be as charismatic," Morgan said.
But it is that charisma that has made Johnson, and in turn the UK, so popular with the Ukrainians -- even though he did not support some of Kyiv's key demands. Like the rest of NATO, the UK refused to impose a no-fly zone over Ukraine. Britain also lagged behind other European countries in its support for Ukrainians seeking refuge, refusing to drop visa requirements. Yet the UK never drew the criticism that Zelensky didn't hesitate to level at others.
While the material support is likely to continue in the near term, the long term strategy might shift.
Kellner said that like his hero Churchill, who demanded Germany's unconditional surrender in World War Two, Johnson has argued for a strategy of complete victory over Russia, and against any compromise.
"If there comes a point where a negotiated end to the fighting becomes possible, Britain's new prime minister might not press Zelensky as forcefully as Johnson has done to say the war, with its deaths and destruction, should carry on to the bitter end," he said.
The war in Ukraine is likely to drag on for a long time. Without the support of the West, Kyiv cannot defend itself against an enemy that has resources several magnitudes larger.
With the British public facing a deep cost-of-living crisis, a British prime minister who is willing to spend money on helping a country thousands of miles away will be crucial for Kyiv.