Russia has mounted a prolonged, sophisticated campaign to meddle in Britain’s democracy, according to a long-delayed report released on Tuesday by a British parliamentary committee, but it is not clear whether its tactics swayed one of the most consequential votes in modern British history: to leave the European Union.

In saying they were unable to make that judgment, the report’s authors directed some of their harshest criticism not at Russia, but at successive British governments, which they said had ignored years of warning signs about Russian malfeasance. Even after questions about the 2016 Brexit referendum, the report found, intelligence agencies failed to properly investigate whether Russia’s actions altered the outcome.

It raised a troubling question: Who is protecting British democracy?

“No one is,” was the answer given by the authors.

“The outrage isn’t if there is interference,” said Kevan Jones, a Labour Party member of Parliament who served on the intelligence committee that released the report. “The outrage is no one wanted to know if there was interference.”

The release of the report came more than seven months after Prime Minister Boris Johnson’s Conservative Party racked up an 80-seat majority in Parliament and almost 18 months after the end of the inquiry by the Intelligence and Security Committee, a parliamentary body that oversees the country’s spy agencies.

Still, it was eagerly awaited in Britain, where anxieties about Russia’s behavior range from influence-peddling with oligarchs in London to the poisoning of a former Russian intelligence agent and his daughter in Salisbury, England.

The report also landed in the heat of an American presidential election, shadowed by questions about ties between President Trump and Russia, as well as fears of renewed foreign tampering, not just by Russia, but also by China and Iran.

The committee’s account characterized Russia as a reckless country bent on recapturing its status as a “great power,” primarily by destabilizing those in the West. “The security threat posed by Russia is difficult for the West to manage as, in our view and that of many others, it appears fundamentally nihilistic,” the authors said.

Experts said the report showed parallels between Britain and the United States in the failure to pick up warning signs, but also important differences. The F.B.I. and other American agencies, they said, had investigated election interference more aggressively than their British counterparts, while the British were ahead of the United States in scrutinizing how Russian money had corrupted politics.

“This is one of the pieces that is not really well understood in the U.S.,” said Laura Rosenberger, director of the Alliance for Securing Democracy, which tracks Russian disinformation efforts in the United States. “Whether there is dirty Russian money that has flowed into our political system.”

The report described how British politicians had welcomed oligarchs to London, allowing them to launder their illicit money through what it called the London “laundromat.” A growth industry of “enablers” — lawyers, accountants, real estate agents, and public relations consultants — sprang up to serve their needs.

These people, the report said, “played a role, wittingly or unwittingly, in the extension of Russian influence which is often linked to promoting the nefarious interests of the Russian state.”

Several members of the House of Lords, the report said, had business interests linked to Russia or worked for companies with Russian ties. It urged an investigation of them, though it did not name any names. That information, as well as the names of politicians who received donations, was redacted from the public report, along with other sensitive intelligence.

“The most disturbing thing is the recognition of what the Russian government has gotten away, under our eyes,” said William F. Browder, an American-born British financier who has worked extensively in Russia and provided evidence to the committee. “The government, and particularly law enforcement, has been toothless.”

The report painted a picture of years of Russian interference through disinformation spread by traditional media outlets, like the cable-TV channel RT, and by the use of internet bots and trolls. This activity dated back to the Scottish independence referendum in 2014, but it was never confronted by the country’s political establishment or by an intelligence community with other priorities.

Focused more on clandestine operations, the spy agencies were anxious to keep their distance from political campaigns, regarding them as a “hot potato,” the report said. Nor was it clear who in the government was in charge of countering the Russian threat to destabilize Britain’s political process. “It has been surprisingly difficult to establish who has responsibility for what,” the report said.

Despite pressing questions, the report said the government had shown little interest in investigating whether the Brexit referendum was targeted by Russia. The government responded that it had “seen no evidence of successful interference in the E.U. referendum” and dismissed the need for further investigation.

But the committee suggested that the reason no evidence had been uncovered was because nobody had looked for it.

“In response to our request for written evidence at the outset of the inquiry, MI5 initially provided just six lines of text,” the committee said. Had the intelligence agencies conducted a threat assessment before the vote, it added, it was “inconceivable” that they would not have concluded there was a Russian threat.

Among the report’s most politically salient conclusions might be about a Russian influence campaign during the Scottish independence referendum. Nationalist sentiment is surging again in Scotland, partly because many voters consider the Scottish authorities to have handled the coronavirus pandemic better than the government in England. Based on its previous behavior, some experts said, Russia would try again to encourage the fracturing of the United Kingdom.

“That obviously has implications for next year’s Scottish elections, and the polling on referendums,” said Bronwen Maddox, director of the Institute for Government, a research institute in London. “All this is very, very relevant.”

Concerns about Russian meddling and aggression stretch back more than a decade to the death in 2006 of Alexander V. Litvinenko, a former K.G.B. officer and critic of the Kremlin, who was killed in London using a radioactive poison, polonium-210, believed to have been administered in a cup of tea. An inquiry concluded that his killing “was probably approved” by President Vladimir V. Putin.

In 2018, another former Russian spy, Sergei Skripal, and his 33-year-old daughter, Yulia, were found seriously ill on a bench in Salisbury, after a poisoning attack that left them hospitalized for weeks. Britain accused two Russians of using a rare nerve agent to try to kill Mr. Skripal, and expelled 23 Russian diplomats in retaliation.

Although the report was approved by Downing Street in 2019, its release was held up before the election that gave Mr. Johnson his decisive parliamentary majority. Critics said he had been compromised by donations to his party from wealthy Russians living in Britain and they argued that the report was delayed unnecessarily.

After the election, there was a second delay while Downing Street agreed on the membership of a new Intelligence and Security Committee.

While the publicly available part of the report unearthed little new material, one expert said that it underscored the need to widen the focus and improve the coordination of Britain’s intelligence apparatus.

“We did know most of this,” said Martin Innes, director of the Crime and Security Research Institute at Cardiff University, “but people were not joining the dots and seeing that quite a serious situation was developing.”

“What Russia wants is to be able to play great power politics,” Professor Innes said. “And one of the ways of doing that is by destabilizing the U.K. and some of its close allies to create that space to maneuver.”


*** The government has now released a 20-page response to the report's findings, which you can read in the attachment here below.