Mumford And Sons, Rihanna, The Killers, Emile Sande, The Script, Two Door Cinema Club, Alt-J, Paloma Faith, Jake Bugg, Of Monsters And Men, Azealia Banks. More TBA. Scotland's biggest outdoor festival is turning 20. To celebrate, they're laying on a typically awesome mix of big name rock and pop acts, with banjo-plucking globe-trotters Mumford And Sons, sultry pop princess Rihanna and Las Vegas' finest, The Killers, all coming along to wish them many happy returns. Mercury-winners Alt-J, hip hop queen bee Azealia Banks and soul-pop songstress Emile Sande bolster this formidable bill and there's still plenty of acts left to be announced. One birthday party you won't want to miss.