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Published 22:06 30 Jul 2018 BST

In exchange for entering a competition to win one of the bottles, entrants had to provide an email address.
Personal data has developed increasing importance for political parties, as indeed for businesses. The Conservative Party spent £2.1 million on digital advertising during the 2017 general election compared to Labour's £577,269. But for that spend the Tories enjoyed a significantly lower reach on social.Explore more on these topics:
The JOE Film Club Quiz: Week 92
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