It's already legal, licencing it in combination of a number of other changes is surely worth trying, if given the current laws it is such a bad situation. Given you are making th case that it is currently so bad, what changes would you propose?
Sorry, NS et al, shouldn't have used the word 'legalising'. Regarding changes - I'm not really sure. Looking at other work areas that have been licensed over the years - such as temporary work picking vegetables and fruit and run by gang-masters - we still seem to have unlicensed work being done and not that much less than it used to be.
As far as prostitution is concerned, I'd also want to know why women are involved. There seems to be a great deal more trafficking of women both within and from outside the UK taking place, and there also seems to a larger number of younger women going into the profession in order to pay for further and higher education. Then, of course, you get the girls and women who are earning the money to feed drug habits. All of these seem to be issues that licensing won't deal with, and need to be addressed first.