You’d never guess it, but Britain is a lucky country. Across the democratic world, Russia pursues its interests by corrupting elections with black propaganda. But in their insouciance, our government and intelligence services show dear old Blighty has no reason to worry. On the rare occasions it bothers to discuss the subject, the British state says “it can’t happen here”, even though “it” is happening everywhere else.

The FBI is investigating how Russia hacked the Clinton campaign and used Facebook and Twitter to spread fake news. Ukrainians are preparing for the next stage of resistance to Russian forces. European foreign ministries and intelligence services have finally understood that Russia’s imperial strategy is to weaken the EU and Nato in every country except, it seems, this sceptred isle.

Russia knows its best tactic is to use migrant crises to stoke nativist fears. “German government threw their country under feet of migrants like a rug, now try wipe their crimes under carpet,” tweeted the Russian embassy in London in 2016 as the Kremlin began a successful campaign to promote the interests of the chauvinists in Alternative for Germany. A bank close to Vladimir Putin loaned $10m to Marine le Pen’s anti-EU Front National. He encouraged the anti-immigrant Freedom party in Austria, the Lega Nord in Italy and Jobbik in Hungary.

Liberals and socialists in the 19th century feared Russia as the world’s greatest reactionary power. So Putin wants it to be again. He is uniting the anti-immigrant, illiberal and, as often as not, misogynist and homophobic forces in Europe and the US into a far-right version of the old Soviet Comintern. Here’s a puzzle: although Britain is the only country to do exactly what Russia wanted it do and leave the EU, there is no British equivalent of the FBI investigation. Journalists have tried to fill the gap. My indomitable colleague Carole Cadwalladr and others have thrown themselves at the story.

On Thursday, the Labour MP Ben Bradshaw used parliamentary privilege to offer support by raising a report on the openDemocracy news site about “dark money in the EU referendum”. It asked “new questions today over the real wealth of Arron Banks, the main financial backer of Leave.EU”.

Given the widespread public alarm about “Russian, interference in western democracies”, Bradshaw continued, would the government investigate?

The report’s authors, Alastair Sloan and Iain Campbell, bring together what others have already discovered and add details of their own. Although it is packed with information, including responses from Banks’s lawyers, the argument boils down to this. In 2013, regulators in Gibraltar discovered that Banks’s insurance business had reserves far below what it needed. Yet a year later the apparently embattled Banks was still able to pour money into the propaganda campaigns that took us out of the EU. He gave £1m to Ukip in 2014. He followed up that small fortune with £9.6m to Leave.EU and Better for the Country Ltd, along with additional cheques for Ukip as the referendum drew near. How did he afford it?

In June, Lionel Barber, the editor of the Financial Times, raised the same question. After his paper investigated Banks’s real worth, Barber asked on Twitter: “How rich is he really?” Banks gave a Trumpian reply: “I founded and sold a listed insurance business for £145m! Not even mentioned – no FT, fake news.”

We have a dispute. To say it is in the public interest to resolve it is to put the case as mildly as you can. But the odds are that journalists won’t nail down the truth if the state does not want us to find it. “Where’s the smoking gun?” critics always cry. Without the lethal weapon, you don’t have a story. The crime-scene imagery misses the point that 99 times out of 100 it’s the police who have the power to find gunmen – not reporters. We can’t arrest suspects. We can’t interview them under caution and obtain warrants to search their homes. We don’t have subpoena powers and forensic laboratories. We are just citizens with keyboards. On occasion, we can nail a target with hard work, resources and luck. But never forget that the greatest of these is luck.

Journalists, for instance, can’t follow the example of the US, where the FBI has arrested George Cottrell, a former aide to Nigel Farage, on money-laundering charges and cut a plea-bargain deal in return for his testimony. We must wait and hear what he has to say. But his evidence won’t invalidate my point: the absence of a British equivalent of the FBI investigation will, in all likelihood, kill the story here.

Britain’s only inquiry into the Brexit vote is run by the Electoral Commission, whose powers Bradshaw aptly described as “pathetic”. His Labour colleague Paul Flynn told the Commons that the commission has “no mechanisms to find out whether there has been interference by cyber-techniques from Russia, by botnets and by artificial intelligence”. The “organisations that may well have rigged the result of the referendum” could sleep easy.

The British government ought to be vigilant to threats to our democracy, but a government committed to Brexit has no incentive to order an inquiry that might cast doubt on the tactics of the Leave campaign. Like the Trump administration, it is desperate to “move on”. All Boris Johnson has done so far is attack Jeremy Corbyn for appearing on Putin’s propaganda channel RT (Russia Today). Just because Johnson opens his mouth doesn’t mean he is lying. The foreign secretary inadvertently revealed why the opposition frontbench is as keen as the government frontbench in airbrushing Russia from the history of modern Britain.

For alongside the leaders of the pan-European far right, who RT welcomes into its studios, alongside anti-European Tories, the cranks, creeps and conspiracy theorists, sit the leaders of our own Labour left – and not only Corbyn and John McDonnell. Richard Burgon is Labour’s satirically named “justice” spokesman. He has never denounced the injustice Putin brings to Russia and the wider world during the nine occasions RT has had him on air. In this, he is symptomatic of a wider left that calls itself “anti-imperialist” but has nothing to say about Eurasia’s most voracious imperial power.

Russia has little to fear from Britain. The government cannot defend democracy because it is compromised by its endorsement of Brexit. The leaders of the opposition cannot force ministers to act because they are compromised by their complicity with the propaganda machine of a mafia state. If “it” happens here, the British public need never know.