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13 September 2013, 17:08
The 'Little Things' singer met the 'Rocket Man' star backstage and also got a shout out during the gig.
One Direction singer Harry Styles was pictured riding the tube to the Roundhouse in Camden last night (12th September).
The 'What Makes You Beautiful' star was in attendance to watch Sir Elton John perform at the iTunes Festival.
Harry even got a shout-out from the singer during the performance and the pair met up backstage.
Meanwhile, the singer is not the only famous pop star to have been spotted on the tube in recent times.
Rihanna often uses the public transport when she stays in the capital – even taking the tube to her gigs at London's O2 Arena.
One Direction performed at the event last year, and Avicii will take to the stage at the Roundhouse this evening (13th September).
Jessie J, Justin Timberlake and Katy Perry will also be performing at the iTunes Festival 2013 this month.