Jessie J, The Roundhouse, London

"Dirty, dirty, dirty, dirty, dirty, dirty sucka," Jessie J booms (there's a lot of booming) on her smutty, provocative opener "Do It Like a Dude" in front of her young, mostly female audience, one of which is wearing large furry ear muffs. An excellent idea.

The Voice panel judge, shorn of her trademark black bob, is in full confessional mode for this iTunes concert. She admits that she's sad that this will be the last time she'll be playing songs exclusively from her triple-platinum album, Who You Are, before gushing, from what appears to be her upcoming autobiography, that she'd be nowhere without her fans and that she really "appreciates us guys", later "revealing" that she felt like she was "losing herself in Hollywood". Buy a map?

After two melisma-heavy numbers, the verbose warbler, who is sporting black hot pants, stops to say "Can I be real with you right now?", before changing out of her five-inch suede high heels for some more comfy red slippers. Wasn't she being real before? Whether she's sincere or not barely matters to a Roundhouse audience that adore her, deliriously lapping up inane lyrics such as “It’s okay not to be okay" on "Who You Are" and "Rock my world into the sunlight/ Make this dream the best I've ever known" on her number one, "Domino".

Undoubtedly, the brassy 24-year-old R&B singer from Essex has had a giddily successful past two years, bagging a Brit critics choice award, Mobo nominations and sashaying down a long stage to Brian May's wailing guitar on "We Will Rock You" at the Olympics closing ceremony. Her high-profile stint on BBC's The Voice has sealed her fame, a subject the former Brit-school trained singer is keen to bring up tonight, "I feel like I'm in Fame," she maintains, flouncing across the stage. Jessie certainly appears pleased with herself, only briefly looking uncomfortable when her outstanding drummer launches into a drum solo. Not one to be upstaged it seems.

In among the bombast, flashing lights and Rihanna/Katy Perry retreads, there are two moments of relief. Her infectious pop gem "Price Tag" (with the spicy "Ain't about the (uh) Cha-Ching Cha-Ching/ Ain't about the (yeah) Ba-Bling Ba-Bling"), which features a guest slot from Chipmunk, and a rowdy, moderately successful stab at Luther Vandross's smooth, Eighties radio staple "Never Too Much". But they're not enough. By the booming end I was longing for my own pair of ear muffs.