An interesting article, Sriram.
However, having read the article I can find no evidence for your assertion that sex trafficking in Britain is "growing". Sex trafficking is a serious problem - but then it has been a serious problem in most west European countries.
English Law (I don't know about Scotland) has considered the selling of sex not to be an unlawful activity but one hemmed in with all kinds of restrictions with the result that some kind of infringement would almost always occur - soliciting, sharing premises, living off immoral earnings etc. One feature of this has been that the women involved acquire criminal records, their customers do not.
What has happened in recent times is that the activity has become industrialised with women recruited from less affluent countries by criminal gangs. The women are tricked into believing that they will be working in legitimate occupations but then find that they are actually sex slaves. Other countries are trying to eliminate the industry by removing demand - by criminalising the customer not the woman. We shall see whether this works.