Independent - Sunday 15th August - has highlighted this story.
In the UK, "Trafficking" has tended to be seen as international and the first anti-trafficking law was framed that way - see Nationality, Immigration and Asylum Act 2002. Obtaining convictions appears to be difficult - see Guardian July 2010 (Prosecutors call on sex trafficking victims to testify). Trafficking within the UK is an offence under the Sexual Offences Act 2003 s.58 - (the offence requires proof of 'mens rea' and that will not necessarily be easy).
There is a UK Human Trafficking Centre which, in April 2010, became part of the Serious Organised Crime Agency. Of course, the government is now planning to abolish SOCA which is seen by Ministers as costly and ineffective - here.
Greater concerted action is urgently required to get a grip on this insidious and appalling crime. The CPS is consulting about its Public Policy Statement - see here.