Diversity?

If you are an employer - particularly if you are a public service employer - to what extent, if at all should the make-up of your staff mirror the make-up of the public at large?  The question has arisen because the BBC have a target that, by 2020 half their workforce will be female, 15% from the ethnic minorities and 8% lesbian, gay, bisexual or transgender - this being apparently the way the general population of this country breaks down.  But we've been down this line before - if you're interviewing someone for a job, surely the overriding consideration has to be - are they right for the post?  Their gender, sexual persuasion and where they were born is surely immaterial. What worries me is the possibility that someone absolutely 100% right for a job may lose out because they are a straight British female and you need a man/lesbian/hindu to make up the percentages.