He is the Eurosceptic gift that just keeps on giving. Indeed, he is possibly the greatest weapon at the Brexiteers’ disposal — more so even than Nigel Farage or Boris Johnson, or those bonkers EU regulations on the correct shape of bananas.

But for how much longer?

Because time is now surely running out for European Commission president Jean-Claude Juncker following the latest evidence of his rank hypocrisy — not to mention his pivotal role in a monumental tax dodge.

As many have argued since last summer’s EU referendum, if the member states of the European Union had not appointed Mr Juncker to run the European Commission in 2014, Brexit might very well not have happened.

A less arrogant, less abrasive, less fanatical Euro-federalist might well have shaved a crucial couple of percentage points off the final 52:48 result.

Fortunately for the Leave camp, the finger-wagging former prime minister of Luxembourg just kept on riling the British public right up to polling day.

European Commission president Jean-Claude Juncker (pictured)  following the latest evidence of his rank hypocrisy — not to mention his pivotal role in a monumental tax dodge

Threat

Indeed, he was at it again just the other day when he warned other member states not to follow the stupid Brits by holding an in/out EU referendum. ‘It is not wise to organise this kind of debate,’ he said.

‘Not only because I might be concerned about the final result but because this will pile more controversy on to the huge number [of crises] already present at the heart of the EU.’

This week, however, a fresh series of leaked documents show the extraordinary extent to which Mr Juncker has spent years blocking EU attempts to crack down on the predatory tax loopholes constructed in his native Luxembourg for the benefit of international corporate giants such as Amazon.

The same documents go on to show how he has also vetoed any public disclosure of these discussions.

So, here we are at the start of a year in which the EU faces the gravest existential threat in its history from a series of national elections in France, the Netherlands, Germany and Italy. And despite crystal-clear demands for greater EU transparency and accountability, the man in charge of the EU apparatus has been rumbled as the architect of a huge tax avoidance cover-up.

As yet, we haven’t heard a squeak from Mr Juncker. Not that we should necessarily believe what he might deign to share with us. This is the man who, while handling the 2011 eurozone crisis, blithely declared: ‘When it becomes serious, you have to lie.’

Well it’s certainly looking serious now.

The latest scandal follows the leak of classified documents involving a secretive EU committee set up to establish a code of conduct on tax policies. The idea was to prevent ‘harmful competition’ between member states.

Since the committee was created in 1998, when Mr Juncker was both prime minister and finance minister in his native grand duchy, the committee has made repeated attempts to toughen regulation.

These have included proposals for investigations of private corporate tax deals with big international corporations. At every stage, these plans were blocked by Luxembourg thanks to a rule requiring unanimity on all the committee’s decisions.

Exasperated by this stalemate, a number of countries including Germany and Sweden then argued in favour of a majority vote. ‘Nein,’ said Luxembourg and vetoed that, too.

So a country with 0.1 per cent of the EU population (think Northamptonshire with fewer people), has been frustrating serious reform of offshore tax avoidance for years.

Then, when it was proposed that the committee’s deliberations might be made public, that also received a big fat thumbs down from Mr Juncker and his compatriots.

Given all the bile which Mr Juncker has directed over the years at the British for being ‘bad’ Europeans, and for obstructing the great European dream, we now find that he has been throwing spanners in the works and getting away with it for years.

There must now surely be serious doubts about this man’s ability to remain at the helm of the world’s most bloated bureaucracy (one in which 10,000 people earn more than the British prime minister).

It was in 2014 that the first revelations surfaced about Mr Juncker’s involvement in cosy Luxembourg tax deals during the 18 years he spent as PM, before being forced out in a phone tapping scandal.

The so-called ‘LuxLeaks’ episode revealed the extent to which companies such as Fiat and McDonald’s had been enjoying potentially illegal arrangements with Luxembourg on his watch — deals which certainly help to explain why it is one of the world’s richest nations.

Several EU investigations have since been commissioned, and Fiat has been ordered to repay tens of millions of euros in unpaid tax, while the McDonald’s case is ongoing. Mr Juncker has supported the EU’s competition commissioner Margrethe Vestager in pursuing these matters.

No doubt Mr Juncker had hoped all these pesky leaks had gone away. Instead, the new disclosures amplify the arrogance of a man who has repeatedly voiced his contempt for the democratic process.

As many have argued since last summer’s EU referendum, if the member states of the European Union had not appointed Mr Juncker to run the European Commission in 2014, Brexit might not have happened

‘I am for secret, dark debates,’ he said in 2011. He also said: ‘We all know what to do. We just don’t know how to get re-elected after we’ve done it.’

Contempt

His attitude towards the inconvenient simpletons the rest of us call ‘voters’, is probably best summed up in his half-jokey, half-menacing prognosis ahead of the 2005 French referendum on a proposed European Constitution: ‘If it’s a Yes, we will say: ‘On we go.’ And if it’s a No, we will say: ‘We continue.’ ‘

No doubt there will be some in Brussels who will try to explain away the latest leaks as rabble-rousing by ghastly Eurosceptic British newspapers such as the Mail.

Actually, the latest Luxembourg leaks have come via German radio, the Left-wing Guardian newspaper and the International Consortium of Investigative Journalists — hardly a cabal of scheming Brexiteers. Indeed, it is increasingly hard to find anyone with positive things to say about the 62-year-old uber-bureaucrat, who makes no secret of his own contempt for the UK.

During Mr Juncker’s quest to become president of the Commission, even that arch-Europhile Lord Mandelson couldn’t come up with anything more enthusiastic than: ‘He may or may not be the nightmare candidate.’

Perhaps now, some of Mr Juncker’s senior colleagues will come to their senses and realise what a liability they have in the man still running the Commission. Then again, perhaps not.

We need only look at the vast new palace which the EU grandees have just unveiled in Brussels. Called Europa — or the ‘Space Egg’ — it is beautifully emblematic of the ivory-towered otherworldliness of the EU elite.

Lies

Originally commissioned for £210 million in 2004, it has finally been finished four years late and £80 million over budget.

Multi-coloured floors and ceilings look like a paint chart but are apparently the work of a Belgian artist-cum-essayist called Georges Meurant, who only paints in squares.

This is supposed to be the new conference centre for both the European Council and the Council of the European Union, with the bowels earmarked for the media and the top floor fitted out as a very grand private dining room. Offices, conference rooms and restaurants fill the space in between.

Indeed, the building has 25 per cent more space for eating and drinking (5,800 square metres) than for actual meetings (4,600 square metres), but then that should come as no surprise to those who have spent any time in Brussels, as I did recently.

Mr Juncker would certainly approve. He is well-known for his love of a traditional European working lunch; one local paper chronicled his heroic consumption of a Campari, three glasses of wine and three Sambucas in just two hours. It’s one of his more endearing traits.

2017 is going to be a very serious year for the EU, one in which voters will decide on its very survival. And yet it continues to be dominated by a pantomime villain who has blamed Britain’s Brexit vote on ‘lies and so many half-truths’ — when, by his own admission, his own career has been littered with the very same.