LONDON—A Brexit campaign group has been found in breach of British electoral law on multiple counts, including the failure to declare payments made to a U.S. Republican political strategist.

The Leave.EU campaign group, which was a vociferous and controversial proponent of Britain’s exit from the European Union, hired the K Street PR firm Goddard Gunster to help shape their rowdy and ultimately successful campaign.

Arron Banks, who set up Leave.EU, credited Gerry Gunster, the CEO of Goddard Gunster, as the man who convinced the Brexiteers that sticking to the facts would not be enough to push Britain out of the EU.

“It was taking an American-style media approach,” Banks bragged to The Guardian a week after the referendum. “What [Goddard Gunster] said early on was ‘Facts don’t work’ and that’s it. The Remain campaign featured fact, fact, fact, fact, fact. It just doesn’t work. You have got to connect with people emotionally. It’s the Trump success.”

Leave.EU was not selected as the official Brexit campaign, encouraging them to take on the role of an aggressively populist insurgent group that reveled in creating controversy to garner free publicity. One such stunt was posting an inflammatory and misleading video that purported to show violent immigrants closing in on Britain with a soundtrack of Donald Trump reciting “The Snake.” Another controversy was unveiling a poster showing a huge line of dark-skinned people with the words “Breaking Point” a few hours before an anti-immigration terrorist assassinated a pro-European Labour politician.

Despite Banks’ public thanks for Gunster, who celebrated the victory with Nigel Farage and Donald Trump in front of a gold elevator at Trump Tower in New York, he would later claim to Britain’s Electoral Commission that Gunster played no role in the referendum campaign itself.

Banks tried to convince the watchdog that Gunster’s advice had come before the official campaign period began or that the advice was given to him in a personal capacity, not to the campaign.

He also claimed that public statements about their work together on the campaign had been inaccurate at the time.

Gunster told Washintonian magazine, for example: “Goddard Gunster embedded staff in the Leave.EU office in London, and I myself spent a good deal of time in the U.K. And it was not just London—Oxford, Manchester, Bristol, the Midlands and more. But while I was in the U.S., my typical day started with waking in the wee hours to respond to emails and hold calls with Leave.EU staff before heading into my office.”

The Electoral Commission found (PDF) that the strategic advice from Gunster had been indeed been part of the referendum campaign and ruled that at least a proportion of over $300,000 in fees payed to the U.S. firm should have been included in the official accounts.

A number of other issues, including loans from companies associated with Banks and 97 missing invoices, were also included in the findings published Friday, although the report found that there had been no secret work with Cambridge Analytica. The commission found they had surpassed strict spending guidelines by at least $100,000, but said it may have been much more.

As a result, Leave.EU has been fined £70,000 ($95,000) and its chief executive faces a police investigation after the report said she had “knowingly or recklessly signed a false declaration accompanying the Leave.EU referendum spending return.”

Despite the breaches of electoral law, the Electoral Commission has no power to offer a democratic remedy or order a re-run of the referendum. A second investigation is ongoing into the Vote Leave campaign, which was the official Brexit campaign, after allegations that they also breached spending guidelines.

Bob Posner, the Electoral Commission’s director of political finance and regulation and legal counsel, said they were unable to push for stiffer sanctions within the regulatory system. “These are serious offenses. The level of fine we have imposed has been constrained by the cap on the commission’s fines,” he said.

Gunster, whose previous success included an anti-soda-tax campaign in San Francisco, has reportedly advised senior GOP figures on a proposed strategy to use populist ballot initiatives to help get grassroots Republicans to the ballot box at the 2018 midterms.

Goddard Gunster, who is not accused of any wrongdoing, did not respond to a request for comment by the time of publication.

Banks, on the other hand, launched his usual publicity blitz following the publication of the report. He vowed to take the officials to court and compared himself to the notorious crime boss Al Capone, who was jailed for the relatively minor offenses of tax evasion.

“The EC went big-game fishing and found a few ‘aged’ dead sardines on the beach. So much for the big conspiracy!” he said. “What a shambles, we will see them in court.”