The Observer revealed this week that Mercer, the owner of Renaissance Technologies (a hedge-fund that specialises in automated trading), a major donor to the Trump campaign and one of the owners of the rightwing Breitbart News Network, “directed his data analytics firm to provide expert advice to the Leave campaign on how to target swing voters via Facebook”. The weekly adds that this donation of services “was not declared to the electoral commission.”

Mercer has a major stake in Cambridge Analytica, a company with a record in psychological warfare operations claiming to use “cutting-edge technology to build intimate psychometric profiles of voters to find and target their emotional triggers”. Donald Trump’s team “paid the firm more than $6 million (€5,7 million) to target swing voters” in the US presidential election, and Mercer introduced it to Farage.

His long-time friendship with the then UKIP leader led Mercer “to offer his help for free to the Brexit campaign”. According to the Observer,

Drawing on Cambridge Analytica’s advice, built up a huge database of supporters creating detailed profiles of their lives through open-source data it harvested via Facebook. The campaign then sent thousands of different versions of advertisements to people depending on what it had learned of their personalities.

Although having declared Cambridge Analytica as “a strategic partner”, the campaign said the company did not work on the Leave campaign and “declined to comment […] on whether it had donated services to,” nor “why it had not declared any donation of services to the electoral commission.” However, the communications director, Andy Wigmore, said to a Guardian reporter that “Cambridge Analytica worked for them”, though pro bono: “It had taught them how to build profiles, how to target people and how to scoop up masses of data from people’s Facebook profiles.”

Neither Cambridge Analytica nor Mercer, who funds a vast array of conservative non-profit organisations, among which the Heartland Institute, a climate change denial think tank, and the Media Research Center, which claims an “unwavering commitment to neutralising leftwing bias in the news, media and popular culture”, were willing to react to the Observer’s findings.