In 2007, British music accounted for 7% of all records sold in the US. Now it's almost double that. What has changed?
In March, One Direction made music industry history, by becoming the first British group to enter the US album chart at number one.
"It was quite surreal," says band member Liam Payne, who at the tender age of 19, has achieved something The Beatles never did.
"I still can't really believe it. We didn't even get a number one in the UK. "
The X Factor graduates aren't the only British boy band making waves in the States. The Wanted recently scored a top three hit with their single Glad You Came - while their new EP peaked at seven in the Billboard charts.
Both have been mobbed by fans on their recent trips to the US. Fifteen thousand screaming girls flocked into New York's Rockerfeller Plaza last month to catch a glimpse of One Direction as they appeared on The Today Show.
Tour manager Paul Higgins says the group can't stay in a hotel for more than three days at a time. Once their whereabouts become known, they require police escorts just to get to and from gigs.
"Hotels love us, because we fill their hotel, then they hate us, because they have no hotel," he says. "It's just taken over by the fans."
"There's hysteria in both camps," acknowledges Max George, of The Wanted.
"One Direction fans are very similar to Justin Bieber's. Ours are like that, too, but we also have fans who are in the bar at the end of the night who'll say, 'oh, I've followed you for a year online'. I like having both.
"Because they buy us drinks," chips in his band mate, Siva Kaneswaran. "And that's great."
But the pop groups' combined success is just the tip of a British music iceberg.
UK acts accounted for 11.7% of all music sold in the US last year. Five years ago, the figure was just 7%.
Adele is largely responsible - her second album 21 was the biggest-seller in the States last year, shifting 5.82 million copies. But acts like Coldplay, Radiohead and Mumford & Sons have also been responsible for sizeable hits over the last 12 months.
"There are a number of reasons why," says Geoff Taylor, head of British music industry body the BPI.
"Obviously, we have fantastic talent in the UK. We are very lucky in that respect. But that's backed up by a music industry that invests at much higher levels than many of our competitor nations."
Taylor says that A&R (artist and repertoire) departments in the UK have proved particularly successful at discovering and developing "unique" voices like Amy Winehouse and Tinie Tempah.
Music journalist Mark Beaumont is more sceptical: "At the moment, UK music is reverting to some pretty basic musical stereotypes," he says.
"If you look at Adele and Ed Sheeran, it's very unchallenging music but it's selling massively.
"People want to be reassured at the moment, so they go for the classic sounds and styles that they know, rather than anything that's challenging or unfamiliar."
All the same, the current wave of British boy ands are outperforming their ancestors.
Take That only managed one hit in the Billboard Hot 100 (Back For Good in 1995). Westlife, who had 14 number ones in the UK, never charted higher than number 20 in the States.
How do the members of One Direction and The Wanted explain their success?
"Basically, it was hard work", says Max George.
"The record label basically said, 'you have to get on radio. If you're not on radio, America's never going to hear you and they're not going to buy the song.'
"They don't have national radio station like Radio One over there. It's individual stations. Each state has two or three main ones, and it can get political if you don't visit a certain one."
So The Wanted toured around dozens of states and cities, shaking hands, meeting radio programmers, and playing acoustic sessions to prove their credentials.
One Direction did the same. Harry Styles describes a typical day: "We wake up somewhere in the morning, have a shower, get dressed, go to a radio station, do some promo, maybe do some interviews. Then we go to the venue where we're performing at night, do another interview, get some food, then do the show.
"Then we drive through the night and wake up in the morning somewhere else."
The radio station dog and pony show isn't enough on its own, however. The current generation's secret weapon is their online fanbase.
Months before One Direction arrived in the US, Columbia Records started a social media competition called "Bring 1D to US," where fans could get the band to come to their city via Twitter and YouTube.
"Literally, people shouldn't know who we are over here at all," notes Harry Styles, "and we've got a little bit of a following because of the internet".
Geoff Taylor says the online strategy is key. "If you've got an established fanbase before you go out there, it puts more influence in the hands of people who are trying to plug an act."
Silvio Pietroluongo, director of charts for Billboard magazine, thinks the answer is much more straightforward.
"Right now we're in a pop music cycle," he says.
In 2007, he explains, the dominant music on Top 40 radio was urban and hip-hop - not genres where the UK punches above its weight.
Then the Black Eyed Peas hired French DJ David Guetta to produce their global smash I Gotta Feeling, and daytime radio turned on its heel.
"Dance pretty much replaced hip-hop," says Pietroluongo. "You bring that kind of music in, and it opens the door for pure pop music as well."
"That was a huge advantage," agrees The Wanted's Max George.
"Our sound wasn't necessarily what people were already listening to, but it was something they could accept."
Pietroluongo doesn't even believe that new acts need to spend months "breaking the US" any more.
"Adele wasn't exactly out and about promoting her record," he observes. "I think the song transcends everything at the end of the day."
With that statement comes a warning, however. In the era of YouTube and Twitter, bands are being discarded with dizzying speed.
"There is no guarantee for a second or third single," says Pietroluongo.
"The mindset of radio programmers is the same as the mindset of consumers: You have to keep me happy with the song.
"As we progress away from an albums market to a singles market, with digital downloads and streaming, I think you're going to see more of that - where the follow-up songs need to sustain that momentum.
"You won't be guaranteed a spot because of who you are - and that goes for superstar acts, too."
It's something which the members of One Direction know all too well.
"I feel like we're doing well in America, but I wouldn't say I feel like we're breaking America," says Liam Payne.
"This industry moves so quick. You might have a lot of hype but you've got to back it up with record sales. It's really important for us to knuckle down and make another great album - because no band can live off one album."
The Wanted have retreated to the studio to plan their next assault on the US, too.
"Over the last four days we've written over 20 songs," says Siva.
"We've become more experienced songwriters over the last three years. The percentage of bad songs has lessened. I think in the last few days we've made a couple of hits."
But the band are realistic about their position.
"A lot of people who bought Glad You Came aren't sure if they're ready for a boy band," says Max George. "They're not necessarily going to buy an album, so we'll have to keep working at it."
And what advice do the boy bands have for those that follow?
"It's tough going," says Harry Styles "but I guess the accent helps."
One Direction interview by Greg Dawson. The band launch their US tour this week. The Wanted's new single, Chasing The Sun, is out now.