LONDON—The CEO of Cambridge Analytica, a political advisory firm that became infamous after Brexit and the election of President Trump for its supposedly decisive use of Facebook data and “psychographic” voter analysis, told Britain’s parliament Tuesday that the company had not actually used Facebook data, or “psychographic” modeling in the U.S. presidential election and had no involvement whatsoever in Britain’s Brexit referendum.

Alexander Nix appeared before a parliamentary select committee hearing on “fake news” to examine ways in which campaign firms like his might help to spread propaganda or disinformation. He said widespread claims about Cambridge Analytica’s involvement in Brexit had been made by an “overzealous PR consultant... Somewhat ironically this was an example of fake news" he told a panel of politicians gathered in the Thatcher committee room inside the House of Commons.

The suggestion of a crucial relationship between Brexit and Cambridge Analytica, which has counted Steve Bannon and reclusive hedge-fund billionaire Robert Mercer among its investors, came directly from Cambridge Analytica and the Brexit campaign group Leave.EU themselves.

Nix admitted that the company had indeed announced it had already begun working for Leave.EU, publicly described the work it was doing for the campaign, and even appeared at the group’s launch event. Arron Banks and Andy Wigmore, who ran Leave.EU, have regularly offered plaudits for the great work done on their behalf to secure Brexit—including in the book Bad Boys of Brexit, which described when they had hired Cambridge Analytica and what it did to help.

Nix said Tuesday that all of those announcements had been mistaken. “We dated each other, we had a couple of dinners, but we didn’t get married,” he said.

Banks, who was watching the livestream of the committee hearing, claimed on Twitter that the business relationship had not gone further because Cambridge Analytica had offered to raise millions of dollars from backers in the U.S. to help pay for its Brexit services.

“CA wanted a fee of £1m to start work & then said they would raise £6m in the states. We declined the offer because it was illegal,” wrote Banks.

An undisclosed donation from foreign sources would not be permitted under British electoral law. The panel put Banks’ intervention to Nix, who denied it.

Another of those watching the exchanges online was Julian Assange, who remains in self-imposed exile inside the Ecuadorian Embassy in London.

He first tweeted a link to the testimony livestream and then—around half an hour later—quoted Nix saying: “We have never spoken to anyone at WikiLeaks” and included another link to the parliamentary site.

Late last year, The Daily Beast reported that Nix had approached Assange by email to offer to help release emails that might damage Hillary Clinton’s presidential campaign. Assange confirmed to The Daily Beast that this exchange took place: “We can confirm an approach by Cambridge Analytica and can confirm that it was rejected by WikiLeaks.”

After denying that anyone at his firm had spoken to Assange, he told the panel Tuesday that Cambridge Analytica had never worked directly with WikiLeaks.

Later, he admitted that he had reached out via a public-speaking agency to try and arrange a meeting with Assange after seeing stories in the media speculating that there may be further explosive emails to come. “We read about these claims, we had no idea whether it was true or not so we reached out… asking whether he would like to meet to discuss this,” Nix said.

The Daily Beast has reported that Cambridge Analytica’s work for the Trump campaign is being looked at by the House Permanent Select Committee on Intelligence (HPSCI) as part of its investigation into Russian meddling.

Bannon, the former White House chief strategist, sold his Cambridge Analytica stake—which was valued at between $1 million and $5 million—in April 2017. He only informed the government that he had done so in November, earning him a late-filing fine.

Nix told the panel that Bannon had been invited to join the board in order to help Cambridge Analytica “penetrate” the American political arena.

He said the company had been hired by the Trump campaign after using its controversial “psychographic” voter-analysis techniques—which purported to be able to understand and target voters’ personal fears—to help Ted Cruz in the Republican presidential primary. Despite admitting that the firm had been able to transfer the data it had gathered from the Cruz campaign over to the Trump team, Nix said it did not have time to implement those methods during the general-election campaign.