This idea of women only lists has been around for quite some time, and i have never understood why such lists do not contravene the various anti discrimination laws we have in this country.
They may well have a laudable intent, such as correcting large imbalances in representation, a good example of which would be the under-representation of women in parliament, but such instruments as women- only lists are discriminatory,clumsy and often anti-democratic, riding roughshod over the local party interest and breeding resentment against any candidate successful through such a mechanism.
I would have thought that such initiatives, like the whites only policy of the BNP, are illegal, and I have never understood why they never seem to be challenged in court.