From huge donations to political parties and bids for games of tennis with senior ministers, to nominations for peerages, Russian money in British politics has been a recurrent issue for years.
But the invasion of Ukraine has intensified calls for party finances to be cleaned up.
Anti-corruption activist Bill Browder, formerly a major investor in Russia, said it is not just the ruling Conservative party that is affected.
"Over the last 20 years it's grown up on both sides of the political spectrum," Browder, whose Russian lawyer Sergei Magnitsky died in prison in 2009, told AFP.
In July 2020, the UK parliament's powerful Intelligence and Security Committee (ISC) laid bare the extent of the issue.
"Several members of the Russian elite who are closely linked to (Vladimir) Putin are identified as being involved with charitable and/or political organisations in the UK," it said.
That "positions them to assist Russian influence operations", the cross-party grouping warned.
But the committee criticised the government for failing to look into possible meddling in UK politics, particularly the divisive 2016 referendum on European Union membership.
Amazing discovery by the @navalny team. The largest superyacht in the world, the Scheherezade, rumoured to be owned by Putin has a 100% Russian crew who are all employees of Russia’s version of the US Secret Service (the FSO) https://t.co/bBtMQZqR9e
— Sir William Browder KCMG (@Billbrowder) March 22, 2022
Fundraisers
Prime Minister Boris Johnson, who has stonewalled calls for an investigation into the manner of his Brexit success, and his Conservatives have come in for particular scrutiny.
The main opposition Labour party accused it of having received nearly £2 million ($2.6 million, 2.4 million euros) from wealthy Russian donors since Johnson came to power in 2019.
Donors include Alexander Temerko, a former top Russian defence ministry official and executive at the oil giant Yukos, and Lubov Chernukhin, whose husband, Vladimir, served in Putin's cabinet before falling out of favour.
Lubov Chernukhin has been described in the British media as the largest donor in the history of the Conservative party, having donated more than £2 million since 2012.
“We do not raise money from Russian oligarchs,” says Boris Johnson.
— Adam Bienkov (@AdamBienkov) February 23, 2022
One of the Conservative Party's biggest donors is Lubov Chernukhin, whose wealth comes from her husband Vladimir, who was secretly funded by a Russian oligarch with close ties to Putin. #pmqs pic.twitter.com/MyQzyFclsX
She famously paid tens of thousands of pounds at a Tory fundraiser to play tennis with the then prime minister David Cameron and with Johnson.
In 2014,Tories accepted £160,000 from Lubov Chernukhin - wife of Vladimir Putin's deputy finance minister - payment for a tennis match with Boris Johnson. The same donor paid £30k for lunch with Education Sec Gavin Williamson.
— StrongerStabler (@StrongerStabler) July 17, 2020
Tories happy to accept the rublel!#ToryCorruption pic.twitter.com/vOtDDce0k4
She also took part in an evening with Theresa May, who succeeded Cameron at Downing Street, and current Foreign Secretary Liz Truss.
Labour wants the Conservative co-chairman Ben Elliott, who is in charge of party fundraising, to resign because of his links to wealthy Russians through his elite concierge company.
Johnson is also facing scrutiny over the appointment to the unelected House of Lords of his friend Evgeny Lebedev, whose father, Alexander, was a KGB agent.
Boris Johnson pulled strings to give his Putlin-linked friend a seat in at the heart of our British democracy.
— Angela Rayner (@AngelaRayner) March 18, 2022
Why should this billionaire son of a KGB spy have more influence in our democracy than the voters of this country? https://t.co/412UaXOOMm
According to the Sunday Times, when he was foreign secretary Johnson attended parties at the younger Lebedev's luxury Tuscan villa.
But British-Russian Lebedev, who owns the London Evening Standard and Independent newspapers, has denied being a Russian stooge, and like Temerko has denounced the invasion.
'Security threat'
The Tories themselves maintain that all donations are registered, legal and come from naturalised British citizens.
In turn, they have accused Labour of "rank hypocrisy" for having received £1 million in donations from individuals of Russian origin.
Peter Goldsmith, a former attorney general under Labour ex-prime minister Tony Blair, took leave of absence from the House of Lords after reports his law firm accepted work for foreign clients, including the Russian government.
Tory Lord Greg Barker has resigned from his position as head of EN+, a mining giant whose principal shareholder is the now sanctioned Oleg Deripaska.
The ISC in its report said it was "notable that a number of members of the House of Lords have business interests linked to Russia or work directly for major Russian companies linked to the Russian state".
"These relationships should be carefully scrutinised, given the potential for the Russian state to exploit them," the committee added.
Daniel I. Weiner, director of the Brennan Center for Justice's election and government programme, said: "A donor that is Russian does not mean they support Vladimir Putin.
"That being said, in a country like Russia where even the private industry is intertwined with government, you can't really become an oligarch without the support of the Kremlin."
Browder was blunter in calling Russian money a "national security threat".
"Previous donations should be looked at with great scepticism and there should be no future donations accepted from any Russian or anyone linked to the dictatorship," he added.