Four years ago, Meriel Armitage was so anxious about using the word vegan on her menu she considered dropping it altogether. On Friday night, shortly after dusk, the 34-year-old opened the doors of London’s first 100% vegan pub, its sales pitch very much based on an absolute boycott of animal products.

Standing by the freshly polished bar, as the first customers arrived into the dimly lit room where all food, drinks, fixtures and fittings are purely plant-based, Armitage smiled: “Back then, we were genuinely worried about putting customers off; suddenly it’s the opposite.”

The arrival of the Spread Eagle in east London’s Homerton, occupying a prime spot on a hipster artery stretching from central Hackney, coincides with unparalleled enthusiasm for veganism.

This month’s Veganuary has enticed at least 100,000 to give up all animal produce for the month, a 40,000 rise on last year. Little more than 3,000 took part in its inaugural outing in 2014. Global brands have spotted the potential, Pret a Manger launching its vegan range a week ago. On Monday, Britain’s biggest supermarket, Tesco, unveiled its range of 100% plant-based meals to be sold in 600 stores.

For Luke McLaughlin, co-founder with Armitage, the Spread Eagle’s arrival marks the start of the next phase of veganism’s move into the mainstream. “A year ago, we would have been nervous about opening, but not any more,” he said.

His confidence was justified by the early flurry of customers. A group of London food bloggers, who knew each other through their admiration for all things vegan, were among the first to place an order with Armitage’s kitchen. Admiration greeted the arrival of tacos with vegan chorizo, vegan fried chicken scallops and beer-battered “tofish”.

Kishani Widyaratna, 32, was among those wowed: “It’s exciting to be here, veganism is growing fast.” Her friend Hannah Siery, 35, nodded eagerly: “The Tesco range was such a big step, the buzz around veganism has never been like this.”

McLaughlin, 38, from Rochdale, predicts the Spread Eagle will prompt a surge in similar vegan ventures around the capital, six years after Soho’s Coach and Horses gained kudos as London’s first vegetarian pub. Research suggests there are more than half a million Britons following a vegan diet. Another food blogger predicted that the rise of veganism will result in a Britain split between vegans and meat eaters. “There’ll be no middle ground any more, just a divided nation,” said Sareta Puri, 34.

Hackney resident Erin Hackett, tucking into a plate of corn esquites, believes it will gradually become the norm to eat less meat. “Meat used to be more of a treat for our father’s generation and I can see a return to that,” said the 31-year-old.

Facebook Twitter Pinterest The Spread Eagle, on Homerton High Street, Hackney, attracted a crowd on its opening night. Photograph: Sophia Evans/The Observer

Helping drive demand, according to Armitage, are social media and the accumulation of readily available information shining a light on aspects of mass-food production. “It’s become harder to cut yourself off from the realities,” she said. Several of those in the Spread Eagle on Friday cited Simon Amstell’s Carnage, a dark comedy set in the future where older generations suffer the guilt of their carnivorous past, as another defining moment in the evolution of veganism.

That London’s first vegan pub is in Hackney should come as no major surprise. The UK’s first vegan chicken shop, Temple Of Seitan, opened last year and has since drawn crowds of devotees. A vegan Christmas market in the borough drew four-hour food queues.

The Spread Eagle has been popular with the area’s drinkers since 1752 and, on Thursday night, residents were invited to sample its cask ales, brewed without using any animal products. Nine of the pub’s stalwart drinkers turned up, taking their usual stools – their leather seats ripped up and assiduously replaced with synthetic covers – to sample their first plant-based pints. “They said that they’ve never been made to feel more at home and that delighted me. They’re part of this area, it’s rich heritage,” said McLaughlin.

Others had travelled slightly further to sample its fare. Tali, 27, from Los Angeles, was adamant the Spread Eagle is certain to become a trendsetter. “Think of the environmental benefits, the health benefits – what’s not to like?”

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Across her at the table sat Damien Clarkson, 33, the co-founder of Vevolution – a media company devoted to promoting vegan culture. He hosted the recent Tesco launch, and predicted veganism’s takeover might become so rapid that it becomes the dominant positioning of restaurants and pubs. “In five years’ time, the place selling meat will be the odd one out,” he laughed.

Beside him, Judy Nadel, 33, said: “Veganism is not exclusive, it’s for everyone, that’s really my hope for the future.”

By 10pm, the pub was buzzing. Armitage scanning the bustling room, said: “At one point, you would’ve hidden that you were vegan; now it’s a case of being loud and proud. All of a sudden, you no longer feel meat eaters have the upper hand.”