In the June 23, 2016 referendum, 51.89 percent backed leaving the EU against 48.11 percent for remaining, on a turnout of 72.2 percent.
The UK formally left the EU in January 2020.
The Intelligence and Security Committee of Parliament (ISC) published its "Russia" report later that year, examining Kremlin interference in UK politics.
It stopped short of concluding Russia had successfully swayed the result, saying the government and intelligence agencies had avoided investigating properly.
It called the UK a "top target" for disinformation that officials treated as a "hot potato"—partly because agencies had been focused on Islamist terrorism since the early 2000s, sidelining the Russian threat.
Moscow had run similar operations ahead of Scotland's 2014 independence vote, the report said.
Citing marketing agency 89up, it noted that Russian outlets RT and Sputnik published 261 anti-EU pieces on the referendum between January and June 2016, reaching a wider Twitter audience than official Leave campaigns.
After Russia's 2022 invasion of Ukraine, the UK and EU sanctioned both broadcasters.
Researchers at Swansea University and UC Berkeley identified over 156,000 Russia-linked Twitter accounts in Brexit discussions, posting more than 45,000 messages in the campaign's final 48 hours alone – many from bots – aimed at deepening divisions and stoking chaos, the report said.
A separate Commons committee report found Kremlin-linked troll farms had run a wider campaign, and accused Facebook and Twitter of downplaying the interference's scale.
The Russia report also said the UK had welcomed Russian oligarchs "with open arms," letting London become a money-laundering hub as Russian capital flowed into politics and business, earning the city the nickname "Londongrad."
Transparency International found Russians accused of corruption or Kremlin ties bought at least GBP 1.5 billion in UK property between 2016 and 2022, and linked 2,189 companies to 48 scandals involving more than GBP 82 billion.
The only British politician convicted of taking money from Russian agents of influence is Nathan Gill, a former Brexit Party MEP, jailed for 10 and a half years in November 2025 after admitting eight corruption charges over at least GBP 40,000 from oligarchs tied to Vladimir Putin.
Moscow has repeatedly denied interfering in the referendum.
Three former British MPs later demanded a government inquiry into foreign interference in both the Brexit vote and the 2019 election.
In July 2025, the European Court of Human Rights ruled the UK's response, including investigations, the Russia report and the 2023 National Security Act, had been adequate.
(ał/gs)
Source: PAP