The difficulty for employers is that it takes just one employee (whether they be male/female, black/white, gay/straight, old/young) to make a complaint about an oppressive working environment and a feelings of harassment and they are on the backfoot.
In law it is the employer who has to prove they are innocent of such a practice as opposed to the employee having to prove them guilty.
So..............if one women complains that she has been overlooked for promotion because of her gender the first thing an Employment Tribunal will consider is the employers approach to equality. Pictures of semi naked women in explicitly sexual poses stuck to the walls etc will not convince an ET that the employer is taking equality seriously and the claimant is already more than half way to a successful claim.
I am not saying it is right or wrong but that is the way it is.