The last time Britney Spears took to the UK stage, in a 2009 tour to promote her Circus album, she was criticised for miming and a lack of personality.
Given that she had returned to the pop world after a five-year descent from being America's pop darling to a breakdown that was broadcast around the world, she could be forgiven.
Tonight, on a tour of her latest, and seventh, studio album Femme Fatale, the global superstar who turns 30 in December and has sold close to 70 million albums worldwide, is still lip-synching, auto-tuned to the max, and seemingly unashamedly so. That is, except for one track: the ballad "Don't Let Me Be the Last to Know", during which she gives the dance routines a rest as she is suspended on a swing. There's no pretence of a live band as a backing tape is played out on a visible laptop by two digital instrumentalists. But everyone knows that it's not about musicality – it's all about the pop spectacle.
The problem is that tonight's show is not really spectacular enough. Spears's own dancing seems lacklustre, compensated by an impressive cohort of dancers that surround her, energetic acrobatic dancers back-flipping backwards towards her as she sashays in colourful sequined leotards and bikinis.
That tickets were slow to shift for this tour and were slashed to half price in a bid to fill seats, with discount site Groupon offering deals – the vast venue is still not full to capacity – suggest that her star appeal is waning. Strange considering that, in a world so focused on social networking, the star was this month reported to be one of six people in the world to boast more than 10million Twitter followers.
But her devoted fans seem determined to have fun. Spears's electro-stomp songs are created for the dance floor and from the very beginning the crowd are up on their feet. The second half of the show takes it to a new level with single "I Wanna Go", a highlight that has whole crowd pogo-ing. "I'm impressed! Good job, guys that was amazing, wow!" her exclamations to the crowd sounding more like robotic computer game commands rather than genuine emotion.
In the stomping finale, "Till the World Ends", Spears is raised on a swing and angel wings burst from her, as shimmering fireworks fall from the stage top like magical stars. She is still a show-woman, but in a world with Beyoncé's vocals and Lady Gaga's inventive outlandishness, the bar is constantly raised.