Music
The London four-piece, who finished second behind Alexandra Burke on The X Factor last year, sold more than 100,000 copies of 'Beat Again' over the last seven days.
Only 'Bonkers' by Dizzee Rascal has racked up higher weekly sales so far this year.
Last week's number one, 'Evacuate The Dancefloor' by Cascada, falls to two, while Black Eyed Peas leap from ten to three with 'I Gotta Feeling'.
Meanwhile, dance star Chicane - the stage name of Buckinghamshire-born DJ Nick Bracegirdle - debuts at seven with 'Poppiholla'.
Notable gains outside of the top ten come from Beyoncé, who leaps from 52 to 13 with 'Sweet Dreams', and Pussycat Dolls, who rebound from 23 to a new peak of 17 with 'Hush Hush; Hush Hush'.
The top ten singles in full (click for our reviews):
1. (-) JLS: 'Beat Again'
2. (1) Cascada: 'Evacuate The Dancefloor'
3. (10) Black Eyed Peas: 'I Gotta Feeling'
4. (2) La Roux: 'Bulletproof'
5. (4) Lady GaGa: 'Paparazzi'
6. (5) David Guetta ft. Kelly Rowland: 'When Love Takes Over'
7. (-) Chicane: 'Poppiholla'
8. (3) Michael Jackson: 'Man In The Mirror'
9. (13) Pitbull: 'I Know You Want Me (Calle Ocho)'
10. (6) Chipmunk: 'Diamond Rings'
> Click here for this week's top ten albums
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