Calvin Klein or Vivienne Westwood?

Probably Klein, but that's only because I have never heard of Vivienne Westwood. My choices were limited to Lee's or Levi's.

caw

I've never heard of Vivienne Westwood either. I live a sheltered life.

I know Brooks Brothers and Austin Reed!

You could just make something up.

According to FMD, Westwood won British Designer of the Year award in 1990 and 1991 and was awarded OBE in 1992. But "...2000 Vivienne Westwood has become the 'old lady of fashion' not yet completely respectable, but yet respected..." So it looks like she achieved her pinnacle in the early '90s if that's the time frame your story is set in.

However, it also depends on your target audience. Klein is obviously better known to the general public. It's like, riding on a Maybach 62 may be more showy than a Rolls-Royce Phantom and way more so than a typical Mercedes-Benz but some (lotz) readers may be clueless.

Up where I live in Alaska, it was probably Carhartt's. If you were uppity, you went for L.L. Bean.

caw

I have heard of both by dint of being British and sneaking the occasional peek at Vogue magazine. Calvin Klein would seem to be more familiar, possibly because he went into the High Street stores. Do you want exclusive fashion, or accessible?

It shouldn't matter as long as it was a trendy fashion house at the time (since it's for a magazine shoot); just add a little something so that anyone reading the novel will immediately get that it's a high-fashion label.

"We want to do the shoot with you wearing something by Mark Pricey. This silk suit is from his spring collection that he showed in Milano last week." (Just as a crude example.)

Emporio Armani???

Everyone knows Armani. It probably doesn't even matter which head designer was on the hot seat at that time. But if you really want a Brit, how about one from: http://en.wikipedia.org/wiki/British_Fashion_Awards? But then, you may risk non-fashionista readers simply skimming through without knowing the impact.

I'm not sure if you can involve a celebrity photographer like Annie Leibovitz or Karl Lagerfeld (or a Brit/Irish from https://en.wikipedia.org/wiki/Category:Fashion_photographers.) OR you can create one who's a household name to your other chars (everyone screams 'OMG Andy Nuwton's shooting you? OMG OMG I hate you I hate you.')

Make him a Bowery Boy. That'll surely stand out.