The British data firm described as “pivotal” in Donald Trump’s presidential victory was behind a ‘data grab’ of more than 50 million Facebook profiles, a whistleblower has revealed to Channel 4 News.

In part one of Channel 4 News’ ‘Data, Democracy and Dirty Tricks’ investigation, in an exclusive television interview, Chris Wylie, former Research Director at Cambridge Analytica tells all.

In collaboration with the Observer newspaper.