Rumer, Bloomsbury Theatre, London

Rumer's story has all the hallmark highs and lows of a fairy tale. After 10 years on the pub circuit, working jobs from popcorn vender to iPod mender, and coping with complicated family issues, Rumer has finally been rewarded with an Atlantic Records deal, rave reviews, and the icing on this rather sweet cake? Burt Bacharach flew her to his home in California, just to hear her sing.

Rumer (aka Sarah Joyce) is clearly well on her way to stardom. Yet the Anglo-Pakistani beauty is visibly shy as she stands timidly on the Bloomsbury Theatre stage. She winces in the spotlight, as she thanks the audience with sincere disbelief for managing to sell out the venue in just an afternoon. That the credit could be hers doesn't seem to cross her mind.

Nerves keep Rumer's ability reined in at first, but it's already evident that the recurrent comparisons to Karen Carpenter are not misplaced. With her eyes cast downwards in sadness and hands pleading, her vocals on "Am I Forgiven" are a deft blend of bright, shining delicacy and the darkness of genuine heartache.

Wrapped in a turquoise Seventies-style dress, her voice oozes maturity beyond her 31 years on the stunning single "Slow", the first release from her forthcoming album Seasons of my Soul, which is released on 1 November.

"This is the last song," she declares, after barely 40 minutes. As the audience vent their disappointment loudly, she looks sheepishly to her pianist for the lead on whether she can appease them with the songs she has "kept up her sleeve".

"I do feel like a little girl wearing her mum's shoes," she says shyly, before tackling her heroine Laura Nyro's "Stoned Soul Picnic". She is stunning, mastering the fluttering inflections with perfect ownership, and – most of all – she is comfortable at last.