Now, Diamondis is a lass from Abergavenny but tonight, Matthew, she's playing Electra Heart – the eponymous character of her second album – and is trussed up in a pink, full-skirted frock with a toy squeaky dog called Marilyn tucked under one arm. Diamondis claims the dog is becoming a celebrity on its own, saying "she's a threat to my ego". I doubt it, the way the girl swanks about the stage, commanding the band, the audience and herself. Not a note goes neglected by enthusiastic am-dramish posturing. If there is any dent to her confidence it's well hidden and that's no bad thing.
Her performance contains a knowing humour that stops the posturing from becoming irritating and she sails engagingly through her gig. The set for this tour, which follows 2010's The Family Jewels, is a 1970s-style neon-sign-and-light-fest. Had she mounted a stationary motorbike and sung at the Stars and Stripes it would have been no surprise.
Diamondis may be Welsh but she's obsessed with Americana, the song Hollywood being the most obvious tribute to her Stateside fascination. Her focus on America and the American dream serves to make her seem oddly parochial and the kitsch of it all is a little dated.
Still, she is perky and fun, engaging and possessed of a skill for writing damn fine pop songs. She delivers, and isn't that exactly what we want?