Daniel Hannan is an MEP for South-East England, and a journalist, author and broadcaster. His most recent book is What Next: How to Get the Best from Brexit.

What do you suppose was the biggest problem faced by Brexit campaigners last year? The fact that we were up against the entire government machine? The funding imbalance? The inertia bias of a cautious electorate?

Nope. Speak to almost anyone from Vote Leave HQ and they’ll tell you that by far their worst headache was Leave.EU, the wrecking operation set up by Arron Banks. It caused them ten times as many problems as Downing Street did. By the end, they were convinced that Banks wasn’t interested in winning, only in using the campaign as a vehicle to promote himself and Nigel Farage.

I realise that that’s a big claim. How could something calling itself Leave.EU not be primarily focused on, you know, leaving the EU? It may have been hapless and hopeless, but surely it at least wanted to win?

Well, behavioural psychologists teach us to infer motive from behaviour. Ask yourself something. What did Banks do during the campaign that might have made a Leave vote more likely? Almost every day he attacked, in crude and puerile language, other Brexit campaigners, especially Nigel Lawson and Matthew Elliott, Vote Leave’s CEO. But can you recall him ever attacking the EU? Chances are, you can remember only one example: the catastrophic “Breaking Point” poster showing a refugee column in the Balkans. On the day it was published, support for Leave dropped by six points – the single biggest one-day fall of the entire campaign.

OK, you might say, but maybe he was trying to be helpful. Really? What undecided voter, at that stage in the campaign, was suddenly going to be swayed by the image of immigrants in Slovenia? As a way of helping Leave across the line, it was plainly counter-productive. As an attempt to keep Banks and Farage centre-stage, on the other hand, it worked a treat.

Banks and Farage were the Leavers Remainers loved. Craig Oliver, who organised Remain’s media, is frank about it in his readable memoir. Above all else, he aimed to turn the poll into a Cameron-Farage contest. Hence his greatest tactical success of the campaign: offering ITN the Prime Minister for a televised debate, but only on condition that Farage was the opponent. Hence, too, David Cameron’s constant description of the other side as “Nigel Farage’s campaign” whose victory would lead to “Nigel Farage’s Britain”.

Remain’s pollsters were plainly telling them what ours were telling us. Up to 25 per cent of the electorate were broadly Faragiste, and responded to his arguments. But these voters would have crossed a six-lane motorway to vote Leave, Ukip or no Ukip. The voters who might go either way – an unusually high number, around a third of the electorate at the start of the campaign – were Eurosceptic but change-averse. They didn’t like Brussels, but were worried about the impact of Brexit on the economy. They wanted reassurance, not rage. They responded badly to the half-bellicose half-jokey tone of Banks’s campaign. They had a low opinion of Ukip.

And here’s the thing. Banks knew it. Farage knew it. But they didn’t care. Their primary objective was to be seen to lead the campaign, not to win it. If those two objectives were in conflict – and, plainly, they were – the first trumped the second. All of which made for a bizarre alliance between Remain and Leave.EU: they shared an interest in making Leave.EU the voice of Brexit.

They’re still at it. News that Banks is under investigation by the Electoral Commission has naturally delighted the pro-EU establishment, especially the Guardian and Observer. Except, of course, they don’t report this as Banks being under investigation. They report it as “the Leave campaign” being under investigation. But Banks wasn’t the Leave campaign. If he had been, we’d have lost.

There have been technical investigations into both Leave and Remain on compliance issues. But it’s Banks who is attracting the most fevered speculation about where his money came from. No proof of wrongdoing has been found, but the lurid nature of the accusation is being used to suggest that Leave won improperly.

To repeat, Banks’s outfit was not Vote Leave, or even an ally of Vote Leave. Vote Leave was the official cross-party campaign organisation, bringing together Labour, Tory, Green and Liberal Democrat Eurosceptics along with the best elements of UKIP (Patrick O’Flynn, Douglas Carswell, Suzanne Evans). Banks’s organisation spent the referendum attacking the official Leave campaign, which he frankly described in a Times interview as “the real enemy”.

It was no idle phrase. Every day, some new distraction would come our way from Leave.EU. We had lawyers’ letters. Banks himself has written of putting “a tail on Elliott”. We even got to the point where, with days to go before the vote, Banks was giving out the phone numbers of our staff and encouraging people to spam them. Ask yourself again: is this the behaviour of someone who actually wanted Brexit?

As far as the Electoral Commission’s investigation goes, Banks is as entitled as anyone else to the presumption of innocence. Being a boastful, belligerent man-child doesn’t make you a Russian agent. The burden of proof is not reversed when we dislike the accused – a principle that is too often forgotten in politics.

Still, I wish Europhile reporters would stop pretending that Banks was a big player, something they know to be nonsense. In truth, Banks is a charlatan, whose promises repeatedly turn out to be false. Think of his recent record: he pledged to challenge Vote Leave’s designation in court, to stand as a candidate in Clacton, to found a new party called the Patriotic Alliance, to sue Elliott, to organise a pro-Brexit rock festival, to set up a pirate radio station. And yet, despite his conspicuous failure to do any of these things, journalists keep reporting his next empty boast.

Their agenda is clear enough. If they can somehow establish in the public mind that Banks was part of the Leave coalition, and if some impropriety on his part is discovered, they will claim that the result is thereby delegitimised.

In fact, Banks’s chief contribution to the Brexit cause was repeatedly to try to sabotage it. Fortunately, as in much else, he failed.