It's EU law.
https://www.gov.uk/data-protection
"Everyone responsible for using data has to follow strict rules called ‘data protection principles’. They must make sure the information is:
used fairly and lawfully
used for limited, specifically stated purposes
used in a way that is adequate, relevant and not excessive
accuratekept for no longer than is absolutely necessary
handled according to people’s data protection rights
kept safe and secure
not transferred outside the European Economic Area without adequate protection"
And is getting expanded and tightened up in May.
https://www.telegraph.co.uk/connect...ss-networks/bt/data-protection-laws-changing/
"And consent will mean active agreement. It can no longer be inferred from, say, a pre-ticked box. Companies that control how and why data is processed will have to show a clear audit trail of consent, including screen grabs or saved consent forms.
Individuals also have the right to withdraw consent at any time, easily and swiftly. When somebody does withdraw consent, their details must be permanently erased, and not just deleted from a mailing list. GDPR gives individuals the right to be forgotten."