When the Yankees, Red Sox and their respective traveling parties arrived in England this week for the eagerly anticipated London Series, amid all the things they expected to encounter -- the tourist traps like Big Ben and Buckingham Palace, the local fare like tea and crumpets and fish and chips -- they would surely come across something potentially unanticipated:

Baseball fans.

Actual, avid, ardent baseball fans.

• Baseball returns to its origins in London Series

Not that anybody would expect these two clubs to play before an empty house at London Stadium. But because this two-game series that takes place Saturday and Sunday is part of a mission to grow the game in an untapped area, you might assume that any and all locals in attendance will be curious onlookers trying to make sense of what they are seeing. Folks who think a “full count” must be some sort of title of nobility.

Though that will undoubtedly be true of some attendees, there is a small but growing faction of British baseball fanatics for whom this event is akin to a religious experience.

And they have a message for those traveling from the States.

“Don’t expect a lot of cool people who are quite hip and interesting,” says Thomas Pringle, one such fan from West Oxfordshire. “You’re going to get a load of nerds.”

As a co-host for the British podcast “Bat Flips and Nerds” and an administrator of the blog of the same name, Pringle should know. The title comes from a 2016 rant from Hall of Famer Goose Gossage, in which Gossage blasted Jose Bautista for his famous bat flip and lamented that “nerds” are turning baseball into a “joke.”

In England, the joke’s on Gossage, because the nerds are the ones spreading the joy of the sport. They seek each other out on social media. They arrange meetups at local pubs. Heck, one of them -- a British-born fan named Joey Mellows who fell in love with baseball while teaching in Japan -- has even spent the last few months criss-crossing the U.S. in an effort to see 162 Major League, Minor League and independent league games in 2019 and spread the word about the sport back home.

“With these two games, Christmas has come early,” Mellows says. “When I found out about it, I was punching the air and stuff. But the weird thing for me is I didn’t have anyone to talk about with it. My love of it is really insular. I head back to my hometown [Portsmouth in Hampshire, England] at Christmastime and literally I don’t know a single person who likes baseball.”

Up until now, to like baseball in Britain has generally required obsession -- or nerdom, if you will. It’s a sort of prerequisite toward baseball fandom in a country where the games, by and large, are broadcast from across the pond long after dark.

“We’re incredibly passionate and incredibly knowledgeable as well,” Pringle says. “Everyone is just so desperate for information and so desperate to know some news. They’re just trying to consume as much as they can.”

Jon Mackenzie, a freelance journalist and night owl who co-hosts another British baseball podcast, “Absolute Bunts,” agrees with that general hypothesis, even if he self-identifies as a more casual consumer of the sport.

“The subculture tends to be quite homogeneous,” Mackenzie says. “It tends to be people who are really keen on the statistical analysis of games, and it tends to attach itself to nerd culture in the U.K. The more I come across baseball fandom in the U.S. through podcasts and just watching games, American baseball has a much more diverse culture of fandom. We’re very much in the early stage of the evolution of baseball fandom in Britain, and I think a lot of the people who like it tend to be toward the sabermetric end of the spectrum.”

The podcast Mackenzie does with fellow writer Henry Cooke is billed with the premise, “Two men who don’t understand baseball talk about baseball.” It’s more of an entry point for those trying to grasp the game. And if the London Series has its intended effect of turning more Europeans on to the game, such offerings of Baseball 101 could find a wider audience.

But for now, it’s a small but mighty pack of rabid baseball fans in the UK. Many of them have gathered online under the umbrella of the MLB UK Community (@MLBUKCommunity), which arranges live MLB watch events in London using the Twitter hashtag #MLBMeetupsUK.

Hannah Tomlinson, an A’s fan (her uncle used to live in the Bay Area) from Blackburn, Lancashire, who is one of four organizers of the MLB UK Community, says social media has turned her “barren land” of fandom into more fertile ground. It’s helped her find other non-States-based A’s fans in far off places like Sweden and New Zealand, and it’s forged new friendships in England.

“I think, in this day and age especially, it’s an incredibly inclusive sport,” says Tomlinson, who has traveled to 16 ballparks in the U.S. “I don’t think you can say that about many sports, and I’m a huge sports fan. But when I go to baseball games, I always feel included, even if I’m an away fan. I don’t know that we have another sport that brings people together like baseball.”

This is especially evident at the U.K. meetups, where British baseball fans, wearing a wide array of team jerseys, convene several times each season. George Martin, another MLB UK Community organizer who lives in London and is an Astros fan (he discovered the game by staying up late watching Channel 5’s ESPN feeds and took a particular liking to Mike Hampton), says as many as 70 people have shown up to the watch parties at a London bar named Belushi’s, where another meetup is scheduled for Friday, on the eve of the London Series.

You won’t find much trash talk between Red Sox and Yankees fans at Belushi’s.

“The game in England and Britain is not established enough to accommodate the fierce, tribal rivalry,” Martin says. “We can’t afford to take the sword to each other. We’re all part of the same group, even though we root for different teams.”

Anecdotally -- and based off Twitter following -- the Red Sox have the largest audience in Britain (winning four World Series in 15 years probably hasn’t hurt the cause, not to mention that they share the same ownership group as Liverpool Football Club). Martin says the Yankees don’t have as large a presence as you might assume, though perhaps the London Series will change that equation.

What Britain’s established baseball fans hope is that the series brings more people out of the woodwork across Europe.

“We don’t want it to be a case of just London or England or the U.K. involved,” Martin says. “We want fans from the Netherlands, Germany, Italy … it’s for them as well, not just for us.”

For many members of the MLB UK Community, the London Series will be the first opportunity to actually see a Major League game in person.

So yeah, they’ll be nerding out.

“When people are complaining about 10 pounds for a pint of beer or whatever it might be, these Brits aren’t going to mind one bit,” Pringle says with a laugh. “They’re so happy to get involved in baseball any way they can.”