Under the Modern Slavery Act 2015, all commercial organisations carrying on business in the UK with an annual turnover exceeding £36m will have to report on the steps they have taken to ensure there is no modern slavery in their business or supply chain. Companies affected will also need to update their websites.

This requirement came into force on 29 October 2015, but does not apply to a financial year of a business ending before 31 March 2016.

http://www.legislation.gov.uk/ukpga/2015/30/ section/54/enacted