Dewmi Fernando, a 23-year-old tourist from Singapore joined the faithful flocking in growing numbers to the bar in Vauxhall, south London.
She braved the rain to pose in front of the pub's brick front topped with "The Black Dog" signage, and next to a blackboard where the pub's manager has written the lyrics to "The Black Dog" in chalk.
In the song from the "The Tortured Poets Department"/"The Anthology", the 14-time Grammy winner sings about being able to still track an ex-boyfriend's location on her phone.
"Your location, you forgot to turn it off/And so I watch as you walk/Into some bar called 'The Black Dog'/And pierce new holes in my heart," sings the 34-year-old star.
"Swifties", the nickname for members of the American singer's army of fans, immediately set out to identify the notorious "Black Dog".
They quickly concluded it was the Vauxhall pub after discovering that Swift's ex-partner, actor Joe Alwyn, lived nearby.
The star, who has cultivated a tight-knit community of fans on social media, has not confirmed the rumours but they quickly spread and the pub has become one of London's newest attractions.
"It's been quite a whirlwind," Lily Bottomley, events manager for the SC Soho group that owns the pub, told AFP.
While in London, Fernando immediately added the pub visit to her itinerary.
"I have actually been listening to Taylor Swift since I was very young," she told AFP.
"She's part of my growing up years, through my childhood, through my teenage years, and then now in my adulthood, it's like I grew up with her."
Pub boost
Fellow Swiftie Charlotte Garratt, 23, who lives in Bedfordshire, south-east England, and came to London for a day trip with her friend to track down the pub.
"We're always finding like we're detectives or something, looking for what it means or if there's a double meaning or metaphors," she added.
While the pub was not yet full on the afternoon of AFP's visit, all the tables were reserved for the evening, and a steady flow of fans stopped to take photographs of the blackboard.
The sudden attention is a huge stroke of luck for the owners, coming at a time when the emblematic English pub is going through a difficult period.
Over the past two years, pubs have seen their costs explode amid rampant inflation and are struggling to attract customers who are themselves affected by the cost-of-living crisis.
"The Black Dog" pub has, unsurprisingly, decided to cash in on its good fortune by adding "Taylor's Version" burgers and cocktails to its menu.
For last week's album release, the bar offered beers to all fans who could sing a Swift song, before having to relent in the face of an influx of Swifties.
"The last four days has been really, really busy... we're going to have to extend our opening times and closing times to accommodate all of those people," said Bottomley.
Bookings have "considerably increased..., more than usual for a rainy week in April," she added.
"We've definitely seen an impact on sales, the 'Taylor Swift effect'," Bottomley told AFP, but added there had been no known sightings of her in the pub.
The bar is already booked up for all of the star's London concert dates this summer.
However, some accused the pub of going too far after its manager told Sky News that he had looked at security camera footage to see if Alwyn or Swift had visited in recent months.
