Britain's Information Commissioner's office said in a report on Tuesday that the insurance firm co-founded by British businessman and political donor Arron Banks would be fined for $78,370 (£60,000), while the Leave.EU campaign would have to pay $19,000 (£15,000) for breaches of electronic marketing regulations.
"We are investigating allegations that Eldon Insurance Services Limited [trading as GoSkippy] shared customer data obtained for insurance purposes with Leave.EU," the Information Commissioner's report said.
More than 1 million emails sent to Leave.EU subscribers also included marketing for GoSkippy services without their consent, the watchdog's report said.
Commissioner Elizabeth Denham said the audit showed "a disturbing disregard for voters' personal privacy."
The fines "could be significantly higher under data protection law if we find misdeeds," she told the Commons digital, culture, media and sport committee.
Denham's deputy, James Dipple-Johnstone, said the watchdog also had concerns about the use of data for electronic marketing at Vote Leave, the official pro-Brexit campaign group led by Boris Johnson and Michael Gove.
In October, the House of Lords heard from British tycoon and political advisor Lord Alan Sugar on political campaigning leading up to Brexit. Lord Sugar suggested that people responsible for putting Britain in the post-Brexit turmoil "should be imprisoned or at least prosecuted"
"Such as Boris Johnson and Michael Gove for the £350m lie on the red bus," Lord Sugar told the House of Lords.
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