They are the biggest new boy band of the noughties, currently sitting at the top of the singles chart and battling with Robbie Williams for the No. 1 album this Sunday. Their show next February at Nottingham's Royal Concert Hall is a sell-out. So, granted a chat with one of the JLS four, there was only one thing to ask: What are you wearing?
"Some boots, some jeans and a T-shirt," says Marvin Humes, without missing a beat.
Well, it makes a change from the usual questions he's repeatedly had to answer over the past few months since they turned around losing to Alexandra Burke in last year's X Factor final and a rejection by Simon Cowell's record label SyCo, to become the decade's hottest boy band property.
What do they think of Cowell? Do they watch the X Factor? Who is the fittest, Cheryl or Dannii? Actually...
If you are the last man on Earth, with just two women left, Dannii and Cheryl, who do you pick?
"Cheryl for me," he says.
"Dannii's lovely, I love Dannii, she's a sweet girl but Cheryl's just perfect. Very hot."
It was their performance of the current No. 1 single Everybody In Love on the show two weeks ago that gave the X-Factor its series peak with an audience of nearly 14 million.
Humes, who was named after Marvin Gaye ("I was born the year after he died"), is in a room at his record company HQ in London. The label treats them well: at September's MOBO awards in Glasgow the quartet turned up in individual, chauffeured Lotus sports cars.
After picking up awards for Best Newcomer and Best Song, Marvin, Aston Merrygold, Jonathan "JB'" Gill and Oritsé Williams were sent into a room to handpick designer clothes and jewellery. "It's not all the time," says Marvin. "The MOBO Awards had a gifting lounge. We're very fortunate. We do get a lot of freebies, which is great.
"Christmas is taken care of, really."
He's diplomatic about the album battle with Robbie on Sunday; their self-titled debut is vying for the No.1 spot with Williams' comeback release, Reality Killed The Video Star.
"You know what, for us, just to be up against someone like Robbie is incredible," is all he'll say.
The album features nine songs co-written by JLS – unusual for any boy band.
"Yeah, it is, for an act coming out of X Factor. We've been extremely lucky. The label put us in the studio for two months and said, If you come up with the goods they'll make the album."
JLS had been together a year before they entered the X Factor.
"The name came from our British identity," says Marvin. Jack the Lad Swing was a composite of their cheeky onstage persona and the US music genre New Jack Swing that had produced Jodeci and Boyz II Men.
As the eldest of the four, is he, perhaps, the sensible one?
"I'd think the boys would say I am because I'm the oldest but we've all got a sensible streak in us."
Aston gets the most attention, he admits, but not because he's better looking.
"He was like the lead singer towards the end of the X Factor. He's very popular with the fans and hence, popular with the ladies."
And Aston has family in Nottingham, he reveals. Scream! We'll say no more. We don't want you lot camping outside their homes...