As a rule, group efforts are something that come before a solo career--not after a solo career is in full swing. First, the artist makes a name for himself/herself as part of a group, then the artist leaves the group to become a full-time solo artist. That's usually how it works, but with Imogen Heap, it was the other way around; the British singer/songwriter (who is also a classically trained pianist) had been an established solo artist for a few years when she became half of the London-based duo Frou Frou. Although Heap now lives in London, she isn't a native of England's largest city.