You might expect most political candidates who win unexpectedly to celebrate their victory, perhaps with a glass of champagne, and look forward to the challenges of their new role. But on Friday, as thousands of new councillors celebrated their triumphs, some of the unexpected winners were less than happy.

Green party managers apologised to one newly elected councillor in Finsbury Park, north London, who was listed as a "paper candidate", who won unexpectedly. "You'll be great, we'll support you," they said, according to the Islington Tribune.

A paper candidate is someone who is put forward with the understanding that they have little chance of winning, so that a party can appear on the ballot as many times as possible. Reform UK was so keen to get candidates across the country that the party even directly called citizens, including a Guardian journalist, and asked them to stand. But this year's local elections, which saw the Labour party suffer its worst results on record, meant many new candidates were elected.

In Camden, a by-election is already scheduled after a secondary school teacher who was elected for the Greens immediately resigned his seat as a councillor because he was not allowed to hold the position while also teaching in the borough.

So what is it like to win unexpectedly? Tyrone Scott has been a Green party member for 12 years. Four years ago, he was very close to power, losing his race to become a councillor for Hackney by 27 votes. "It was quite devastating at the time," said the 34-year-old. A few months later, he stood for the party's vice-leadership, but came second to Zac Goldsmith, who has since become leader.

He stepped back from politics to take a job at a charity. "It seemed like it was really tough for me to run again, I had a lot of work commitments," he said. He still wanted to run, so he compromised by choosing an area where "there was less likelihood of winning". He was elected in Hackney Wick, where Labour won when the seat was contested in 2022. Despite this, he called himself a "cardboard candidate" rather than a paper one, because the party believed victory was possible across the whole ward.

Activists "did a very small amount of campaigning" in Hackney Wick compared with the rest of the ward, where he had run a year-long campaign.

The first sign that things might be better than expected was a large stack of votes for his ward when they were verified on Thursday. "I had a little feeling, but even then, I really didn't believe," Scott said. Everything crystallised at the count, as the Greens won victory after victory. "The first nine or 10 seats came in as all Greens, including a few surprises," he said.

In a seismic day for the Greens in London, the party gained a majority on Hackney council, unseating Labour as the ruling party for the first time since 2002, winning 42 of 57 seats. Zoe Gibson became the first Green mayor to unseat Labour's 24-year hold on the post.

When the results for his ward were announced and all three elected councillors were Green, Scott said it was "a mix of emotions", including "nervous excitement". "I thought there was a small chance, but I really didn't think I had a shot at all three," he said. "It was pretty surreal, and we were all really excited. I think we all had a moment of: "Oh, wait, this is actually real."

Scott works as a campaign director for a charity fighting poverty. He informed his bosses of his intention to stand, who said he could "go" with the "understanding that it was unlikely I would win". If he did win, his job said they could work around it. "I'm sure they're thinking: "Oh, actually, this is real" and we'll have a conversation when I'm back in the office on Monday," he said.

Scott hopes the Greens will be able to restore "community cohesion" in Hackney and show, especially in the wake of Reform UK's wins across the country, that "we can be a shining example of building hope rather than hate."