There are more than enough clues elsewhere in the question, but I don't think it helps to describe Nicki Chapman as a "music producer". For one thing I don't know what a music producer is; it makes me think of record producer – which Nicki Chapman is not, and (as far as I can make out ) never has been.
Nicki Chapman worked in the record industry from an early age, and became joint owner of a PR company which represented a host of stars including Amy Winehouse, Kylie Minogue and David Bowie. In 2001 she joined Simon Fuller's management company 19 Entertainment as Creative Director, working with acts including Annie Lennox, Will Young, S Club 7 and the Spice Girls. She then got the gig as a judge on Popstars ... and the rest is included in the question.
If you wanted to describe her role in the record industry, you could maybe call her a "music industry executive".
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