Good news regarding positive discrimination in the UK (also known in the US as 'affirmative action') -- buried in comments in this thread:
Most UK philosophers doubtless know this, but lest any are uncertain (as I was), it is worth noting:
That a candidate is a woman now may legally be taken as grounds for preferring her over a man for recruitment or promotion purposes.
This is so only if the candidates are equally qualified, and women are disadvantaged or under-represented in the relevant "activity" (presumably, in our case, academic philosophy), and the positive action is considered proportionate.
(The same applies mutatis mutandis to any "protected characteristic", defined here)
Since I am no lawyer, and this is my gloss, see Section 159 of the Equality Act 2010 for chapter and verse.
Thanks to David for having taken the time to research this.