Each year the Home Office produces a report on the status of modern slavery within the UK. Data is collected from three primary sources with current statistics as follows:

• Referrals of potential victims to the National Referral Mechanism (NRM), the UK’s identification and support system for victims of modern slavery. In 2016, there were 3,804 potential victims referred to the NRM (a 16% increase from 2015), of which around a third (1,277) were children.
• Referrals of potential victims under the ‘duty to notify’ provision of the Modern Slavery Act 2015 which applies to England and Wales. Specified public bodies have a duty to notify the Government if they encounter an adult victim of modern slavery. In 2016, 782 potential adult victims were referred to the duty to notify, bringing the total number of potential victims identified in 2016 to 4,586.
• The number of modern slavery crimes recorded by the police. In the year to March 2017, police in England and Wales recorded 2,255 modern slavery offences, a 159% increase on the previous year. In the year to March 2017, Police Scotland recorded 60 offences and the Police Service of Northern Ireland (PSNI) recorded 35 offences.

For the full UK Home Office Annual Report on Modern Slavery October 2017, read here.