Lady Gaga, Capital FM Jingle Bell Ball, review This year has been a messy one for Lady Gaga. The 27-year-old has endured, and recovered from, hip surgery, released her third album, Artpop, sales of which were overtaken by records from Miley Cyrus and Katy Perry, and most recently, split from her long-term manager, Trey Carter. Bubbling underneath was a path of discovery: she was not - she declared - a product of the pop industry, but an artist. She lived not for meaningless fame, but the applause which arrives after a genuine performance. So why is she finishing off the year by headlining the ultimate teenybopper festive funfest, Capital FM's Jingle Bell Ball? After nude stunts with performance artist Marina Abramovic and collaborations with Jeff Koons, the O2 Arena, full to the brim with glowing jewellery, fake snow and Twitter-formed fan clubs, seemed a bit of a step down. Ten acts preceded her; from the capable Jessie J to the gratuitous Jason Derulo, in a barrage of pounding EDM beats and glitter-cannon eruptions. Little Mix, the 2011 X Factor winners, were the surprising exception: polished and punchy, their upbeat set explained their American chart success. After five hours of constant screaming and lightweight drum and bass - a staple element of 2013"s pop music - Gaga emerged in the most radical way possible: silence. Sat, Liberace-like, by a piano in a purple convertible, wearing a sequined suit, a green-haired Gaga raised a paw to her adoring fans (the so-called Little Monsters) and broke into a stripped-back version of Jingle Bells. Part soaring soprano, part New York snarl, and with doctored lyrics celebrating incontinent reindeer, a resigning Santa and the Jingle Bell Ball, Gaga trumped her warm-up acts in one fell swoop. She proved to be just as naughty, talented and entertaining for the next 40 minutes. During Aura, Artpop's techno track, four androgynous men in bondage outfits strapped her, screaming, into a cage. While singing Pokerface, Gaga purred over the subtext of infidelity. It was a pop performance both outlandish and subtle. Some little ones trooped out half-way through, the whole affair proving too much after a long day. The set list was a pleasing chronological list of her greatest hits: a curtailed Just Dance led into a freestyled Bad Romance before the best of her set, Born This Way ("Where are my gays in the audience?"). But she closed triumphantly on Applause, her comeback single.