I'm about 3/4s of the way through re-reading Catwalk Confidence

I was reminded of another story, the protagonist is similar to Alex's sister Ellen who is a student in couture.

The story begins in the US, Protagonist is a couture reporter I think.
The investigation takes the protagonist back to the UK, London?, where she bagan as a student in couture.

European 'designer' stealing designs from students in couture, who drop out usually for family related reasons.

If I remember right there was mention of the Protagonist purchasing the remainder of a one-off patterned bolt of fabric originally commissioned by Alexander McQueen.