TheRealBabushka, Poshgirl, there are carve-outs in many discrimination laws permitting discrimination where it is to offset an existing gender imbalance or there is another genuine justification for the discrimination. There is also a tie-in with the legal requirements in many countries to ensure a safe workplace. *If* women are seen as being at greater risk of harassment or other dangers when travelling for work reasons, then a lone female traveller policy is not only unlikely to infringe discrimination laws, it may even be something that the employer *should* have in place. Of course there is also the question of whether the dangers are such that there should be a policy for all lone travellers regardless of sex (which might well be the case in some places)!
Poshgirl, my company has women’s networks – and in line with our requirements for other networks, all staff must be permitted to join and participate. Interestingly, on average about one third of the attendees at meetings of the women’s network in London are men.