The world may just be waking up to Imogen Heap, but she’s been one of the most interesting and inspiring artists for more than a decade.

Releasing her first album when she was just 17, Heap makes gloriously uplifting music that combines a technologically inventive approach to songwriting with a real sense of the ethereal.

Long before Florence and the Machine or Bat For Lashes arrived in mainstream consciousness, Heap had already laid down the template for them both to succeed and continues to be a pioneer, on record and in her live performance.

None of this would be possible, of course, without her voice, which has the most astonishing range. It can go from husky to helium-swallowing highness in a split second, as it does many times during her two-hour set in a sold-out O2 Academy.

Heap was to have played here in February, but had to pull out owing to illness and so plays an extra long set to compensate. And it’s a great set, with tracks mostly pulled from her new album Ellipse and breakthrough record Speak For Yourself.

Watching Heap live is a wonderful experience, but she’s exhausting to keep up with. In between songs, she talks, at length, about where each was written and is constantly moving about the stage, making use of what seems like 50 or 60 instruments. She has samplers all over the stage and can build a simple beat into a track that seems to be powered by an orchestra. The whole set is brilliant, but particularly outstanding are her renditions of the epic Earth, thunderous Headlong and the gentle Come Here Boy. Heap has just sold out the Royal Albert Hall, but given she left it seven years between albums the first time round and took another four years to record her third, don’t expect her to be concerned with building on her momentum. She can take her time, she’s earned that right.