IT’S now two years since Ali and Iain first approached me with questions about Arron Banks. Alastair Sloan was an occasional contributor to openDemocracy. Iain was an accountant. In Spring 2017, they came to me with a surprising claim: they had serious doubts about whether insurance company owner Arron Banks, “the man who bought Brexit”, was really anything like as rich as people said.

And so, they asked, how did he have enough to pay for so much of the Leave campaign?

I’d spent the previous months working on our story about dark money being funnelled into the Brexit campaign via the DUP, and their questions ran parallel to ours. So my colleagues and I worked with them over the next few months to stand up their claims, and, that Autumn, I hit publish on their article: How did Arron Banks afford Brexit? Banks had, after all, flooded a fortune into the Leave campaign – by my sums, perhaps as much as £15 million. And if the money wasn’t all his, where had it come from?

The piece raised questions in parliament and headlines around the world and started a new strand of work for us. Eventually, along with others, we managed to get the Electoral Commission to investigate Arron Banks. They concluded that they had “reasonable grounds to suspect a number of criminal offences”, and, after much chivvying, the National Crime Agency eventually opened an investigation into Arron Banks.

Banks will presumably have plenty of advice on how to behave in such an investigation. His long term business partner, Alan Kentish, was arrested in Gibraltar in October 2017 on money laundering related offences, and has had similar run-ins with the authorities in Malta, Jersey and St Kitts and Nevis.

Arron Banks has a political partner, too. And while Banks has, in some circles, become known for the questions around his finances, his partner in politics, the man he (or his secretive backers) has bankrolled, has largely managed to avoid these sorts of embarrassments.

That partner – the front man – is, of course, called Nigel Farage. The two men have worked closely together since they were introduced in late summer 2014 by the Scottish-Manx billionaire Jim Mellon who made much of his fortune from the mass privatisations of the collapsing Soviet Union in the 1990s. (By a strange coincidence, I happened to be on the Isle of Man around that time, and spotted a poster for a talk by Farage in a cafe in the capital Douglas).

Unlike Banks, and with the exception of the Observer’s Carole Cadwalladr, Farage had largely escaped these awkward questions about the money until last week. On Monday, Gordon Brown used one of his famous “dramatic interventions” to highlight questions that Cadwalladr among others had been asking about the finances of Farage’s new party, the Brexit party, which is expected to top the polls in this week’s European elections when the votes are counted.

There has long been a loophole in electoral law that donations under £500 aren’t really monitored. Somewhat bizarrely, UK electoral rules define a donation to a political party as “money, goods or services given to a party without charge or on non-commercial terms, with a value of over £500”. So, in theory, you can take as much money in the form of lumps of less than £500 as you like. And so, sticking to the letter of the law, the Brexit party has popped a PayPal button on its website, and only asks for your name and address if you give £500.01 or more.

During the European election campaign, Farage boasted that his party was being given £100,000 a day, and Brown highlighted the question of whether some of these donations were in fact from a questionable, foreign, or unknown source – what he called “dirty money”, saying that Farage wasn’t so much a man of the people as “a man of the PayPal”.

He called on the Electoral Commission to investigate, which they are now doing.

When Cadwalladr and colleagues wrote up Brown’s speech this week, they also highlighted an important new piece of information: rumours that “posh” George Cotterell is back on the campaign trail.

You see, like Banks, Nigel Farage has a good friend with first-hand experience of money laundering investigations.

Farage was in fact with George Cottrell when he was arrested at Chicago O’Hare airport in July 2016, shortly after the EU referendum.

Cotrell had been working in Farage’s office and, as the paper explained, claimed on his LinkedIn account to have co-directed Ukip’s EU referendum campaign fundraising. He was charged with 21 counts including money laundering, wire fraud, blackmail and extortion and later pled guilty to participating in a scheme to “advertise money laundering services on a Tor network black market website” and served eight months in prison.

Farage said he knew nothing of the allegations.

What was revealed last week was that Cotterell, now out of prison, is said to have told friends that he is working as the Brexit party’s fundraiser. Cadwalladr and co say that they have seen pictures of Cotterell with Farage in the run up to the Euro election, including at Brexit party events.

The Brexit party denies that George Cotterell is working for them, and dismissed the importance of any photographs of the two men together, arguing that lots of people come to their campaign events.

What are we to make of all of this?

First, the UK’s campaign finance laws rapidly need to be updated. The current laws were written in 2000, before online payment services like PayPal was a serious option.

Second, we will need to keep asking questions about the Electoral Commission and police investigations of Banks, Farage and their various friends.

And third, isn’t it interesting that the most prominent Brexiters sit in such close proximity to those who are often accused of hiding and cleaning up questionable cash? Can we really understand Brexit without understanding that the UK and its overseas territories are now the world’s leading money laundry? I’m not sure we can.

open Democracy have been prominent inquisitors of the world of dark money which has been influencing British politics for several years.

They first exposed the DUP’s Brexit donations which involved a secretive group in Glasgow, then turned their attention to the Scottish Tories’, forcing an electoral commission investigation.

Next came Aaron Banks, the man who funded the leave campaign and subsequently, Nigel Farage’s Brexit Party aspirations.