A source at the victorious campaign group told the Guardian that McKenna “understands the psychology of the mind” and helped Leave.EU “produce social media ads that resonated with people”.
McKenna’s role emerged at the end of a week in which several senior politicians backtracked on persuasive campaign messages from the EU referendum on immigration controls and how much money saved from payments to the EU could be redirected to the NHS.
The hypnotist is said to be a friend of Arron Banks, the Bristol-based multimillionaire insurance businessman who bankrolled the Leave.EU campaign with a £5.6m donation.
McKenna became involved as Leave.EU spent millions of pounds building up its online following partly by using short, dramatic campaign videos posted on its social media accounts. It claimed that it had 1 million followers and supporters on social media by polling day on 23 June.
The 53-year old author of bestselling self-help books including The Power to Influence, I Can Make You Happy and Hypnotic Gastric Band was asked by the Ukip-backed Leave.EU campaign to examine early edits of promotional videos.