Brittany Kaiser was one of the whistleblowers who brought down her former employer, Cambridge Analytica. She helped to expose how the data analysis firm had collaborated with Facebook to profile millions of voters around the world, in order to target them with tailor-made propaganda.

In an extended interview, she tells the BBC's Jane Wakefield how our data is still open to abuse by those seeking to undermine democracy by manipulating the way we vote.

(Picture: Brittany Kaiser in Washington, DC; Credit: Bill O'Leary/The Washington Post via Getty Images)