Here's an interesting situation; a shop called Bravissimo is opening up in Oxford, selling lingerie for the larger-busted woman. They recently placed an advert in the appointments pages of the local paper for bra-fitters. Of course they couldn't specify that it was open to women only, because of equal opportunities legislation, but do you think that they would actually invite any male applicants for interview? Assuming that they would be worried about--how can I phrase it delicately--applicants getting an inappropriate level of satisfaction from the job, then they might also be worried about gay women applying. But you can't ask people about their sexuality either, so they seem to have a bit of a difficult task.
What we have here is a modern legal minefield.