I was talking about this last night with friends. One of the OH's oldest friends works in the Head Office. I play myself, and it's how I met the OH.
Apparently, it's because they don't get a lot of applicants at the retail level. Games Workshop's retail is very, very poorly paid and the people who tend to work their are picked because they love it. They look for stable, enthuiastic people who are utterly obssesed with toysoldiers. These tend to be boys who happen to have gotten taller without growing up. They also look for those in a stable relationship, preferably with kids of their own, as a big part of the job is dealing with young boys.
Most of the models are exagerrations; this is a big part of their 'design ethic', it's all big and loud. So the men look like this:
www.games-workshop.com/gws/catalog/productDetail.jsp?catId=cat440247a&prodId=prod30015a
and women look like this:
www.games-workshop.com/gws/catalog/productDetail.jsp?prodId=prod1160051a
the gender-abandoned post-human monsters look like this:
www.games-workshop.com/gws/catalog/productDetail.jsp?prodId=prod680007a
and the giant spider dinosaurs look like this:
www.games-workshop.com/gws/catalog/productDetail.jsp?prodId=prod1460211a
At the Game Design and head office level, it's a lot better; this is the part where they actually make the game, and there is more equality. It still isn't even, but they have female games designers, painters, novel writers, sculptors, senior managers, Human Resource managers, etc. They are also more than a few husband and wife teams, it's encouraged, I gather. If you're good, happy with a below average wage, like toysolders and willing to live in Nottingham, they'll hire you.