War always forces change. If the war against Russia’s mafia state is to be won, or even fought, then the network of tax havens, trusts and shell companies that has made London a global money-laundering centre will have to be busted open.

Senior Conservatives talk as if they understand after Salisbury that the Russian police, secret services, propaganda stations, sporting federations and ministries are not separate institutions but parts of a complete merger of the political and criminal classes. Maybe I am naive, but I believe them when they say they are willing to take on Putin. I just doubt that they understand how much of Britain’s plutocrat-enabling culture must change.

To use the cliche, sunlight has become the west’s disinfectant. Never has the closed world of intelligence been as keen on publicity. The pictures Dutch intelligence released of the arrest of GRU agents attempting to hack the Organisation for the Prohibition of Chemical Weapons performed the same function as the British authorities’ exposure of the Salisbury poisoners. Russian spies no longer appeared to be supernatural figures but blunderers with cover stories a child could unpick. The willingness of the UK and Dutch intelligence agencies to go public has turned Russia into a laughing stock, and Russia, like all dictatorial countries and individuals, can stand anything except mockery.

Don’t laugh too heartily, though. A regime may be simultaneously preposterous and effective. Take the case of Julian Assange, to reach for the closet example of the absurd. Holed up in the Ecuadorian embassy for years because he is not man enough to face the charges against him, he seems the Ben Gunn of the internet age. Yet the Mueller inquiry credibly alleges that Assange was the final link in the Russian state’s operation to help Donald Trump defeat Hillary Clinton. GRU agents passed 50,000 documents from the Clinton campaign to WikiLeaks, which presented them as the product of its own investigations in the journalistic equivalent of money laundering.

We think that modern history is the result of grand forces: the revolt of the white working class, the backlash against globalisation. But it is as likely that supposedly comic Russian spies collaborating with a lank-haired braggart hiding from justice in a Knightsbridge basement, with only occasional visits from Pamela Anderson to relieve the tedium of his wasted life, have changed the world.

Nor can the successes of western intelligence stop Russia spreading fear. The US authorities matched the Dutch and British by revealing every detail of how the GRU targeted international sporting organisations as punishment for their role in exposing doping in Russian sport. It seems a counter-espionage coup until you remember that a frightened World Anti-Doping Agency hastily rehabilitated Russia last month rather than risk further GRU attacks.

Exposure will do little good unless openness by the intelligence services is matched by the breaking of financial secrecy that protects the assets of a criminal regime. As those assets have delivered large commissions to everyone from City banks and law firms to private schools and Mayfair estate agents, it has taken an unconscionably long time for Britain to accept that national security comes before the national income.

Russia, like all dictatorial countries and individuals, can stand anything except mockery

We have been living through a rerun of the 1990s, when the security services refused to listen to warnings from the French that London had become a centre of Islamist terrorism. They did not wake up until the exploding planes of 9/11 shook them from their slumbers. Until Salisbury, the British government treated Russian terrorism and threats to the democratic process with the same wilful neglect. As late as 2014, Theresa May, the then home secretary, was attempting to stop an inquest into the poisoning of Alexander Litvinenko for fear that open justice would harm the Foreign Office’s attempts to mend relations with Putin.

Belatedly, the government is preparing to hit the alleged looters with “unexplained wealth orders” that freeze assets until oligarchs can show they are not the proceeds of crime. A test case last week demonstrated how hard it is to shift a rotten culture. For all ministers’ fighting talk, class privilege still beats open justice in the English courts. The judge said journalists could only refer to a woman, who is being asked to account for how she and husband acquired $72m (£55m), as “Mrs A”. If the police alleged that you or I had stolen £72, our names would be public property. Face accusations of stealing $72m and the judiciary rushes to guarantee anonymity.

The National Crime Agency has deeper worries and wonders how it will prove London’s Russian oligarchs are criminals when the Russian state can provide them with fake property deeds as easily as it supplies its propagandists with fake news. To succeed, the intelligence agencies need to win the trust of the public and, indeed, of the judges. They should be able to release verifiable intelligence not just on oligarchs, but on the lawyers, bankers, accountants, journalists and politicians who work for Putin, and expect a fair hearing.

Trust, however, is impossible as long as the state expects us to believe the transparent falsehood that Britain is the only country in the west where Russia has not tried to rig elections. I can guess why the police and intelligence services have released nothing on the meetings between Leave.EU and the Russian embassy. If they were to do their duty, they would embarrass a Conservative party that was taking Britain out of the EU and a Labour party led by far-leftists who have opposed the EU all their lives. Neither wants the Brexit campaign examined. I do not want to draw a crass moral equivalence between the Russian and British security services, but they are similar in one respect: both put political convenience before the national interest.

Brexit, in other words, is poisoning the attempts to defend British democracy as it has poisoned everything else – which was why Russia was so anxious for Britain to leave in the first place.

• Nick Cohen is an Observer columnist