I am, it seems, a ‘foreign plutocrat’. The considerable sum of money I’ve donated to the Remain side of the Brexit debate is ‘tainted’ and should be handed back immediately. I should ‘butt out’ of British politics. All of this grew out of a dinner party I hosted just a few days ago. I have never made any secret of my opposition to Brexit and, indeed, I made my case quite openly in the pages of The Mail on Sunday at the time of the referendum.

Yet, most damaging of all, I find myself accused of ‘undermining democracy’ – and it is this rather serious charge I would like to address head on.

Perhaps I could say a little about my background and why this country and democracy matter quite so much to me.

The formative experience of my life was the occupation of Hungary by Nazi Germany in 1944. Being Jewish, I would probably have perished had my father not arranged false identity papers and hiding places for his family and many other Jews. I learned at the age of 13 just how important it is what kind of political regime prevails.

Nazi occupation was followed by communist rule, which I found so stifling that I escaped Hungary and found refuge in England, where refugees were then treated much better than nowadays. I spent nine years in this country and became a confirmed Anglophile.

Work took me to New York in 1956, but Britain remained close to my heart. I still have a house in London and spend part of each year there.

While former Chancellor Lord Lamont might criticise my involvement as a foreigner, it might help him to know I also have long had businesses in Britain – in much the same way as has Rupert Murdoch, an American citizen and well-known Brexiteer.

The good thing is that both of us ‘foreigners’ have been more than happy to bring jobs to the UK economy.

As a young man, I was greatly influenced by the years I spent in Britain. I was able to go to the London School of Economics, where I encountered the great Austrian philosopher Karl Popper, who became my mentor.

Under his influence I came to distinguish between an open society – in which people elect their leaders, who are supposed to serve the interests of their electorate – and a closed society, in which rulers exploit the people under their control.

I believe passionately in the former, and this is why I eventually decided to establish the Open Society Foundations and devote my wealth to spreading the benefits of open democracy and helping those that suffer repression.

Open society is characterised by calm, rational discussion, free from the toxic, personal criticism we have seen in recent days.

I am a proud supporter of Best For Britain, a group that wants Britain to remain a member of the European Union. I consider Brexit a tragic mistake.

Prior to Brexit, Britain enjoyed the best of all possible worlds: it was a member of the European Union without adopting the euro.

Allowing a referendum on membership was a fatal error. Experience has shown that referenda often lead to bad decisions. Egged on by unscrupulous agitators, people use them to express their dissatisfaction with the current state of affairs rather than contemplating the consequences. The fact that conditions are unsatisfactory does not mean they can’t get worse. That is what has happened in Britain.

Brexit is a lose-lose proposition both for Britain and for Europe. Politically, Europe without Britain will be weakened in its ability to defend and promote democratic values.

Europe will suffer from the absence of British pressure for the necessary institutional reforms. Economically, Europe will lose its third-largest economy and its strongest advocate of liberal economic policies.

Britain, outside Europe, will lose much of its global influence. Economically, Britain will suffer because 45 years of successful integration with Europe will go into reverse. Divorce is a very destructive process; there is no such thing as a friendly divorce.

It is an illusion to think economic separation can be accomplished in just two years. It will take at least five years and possibly much longer. This process will change Britain and Europe from friends into foes, at least during the transitional period. Before the referendum Britain was doing better economically than the rest of Europe. But this has now been reversed, with continental economies powering ahead while Britain lags behind.

The effect of the uncertainties created by Brexit on the UK economy will become much more painfully obvious in the next six months as the divorce process enters its most contentious phase.

To make matters worse, the divorce process will preoccupy both Britain and Europe for years ahead, when they should be uniting to resist external enemies like Putin’s Russia and resolve the internal contradictions that made some people regard the EU as their enemy.

Brexit has rendered the two-party system outdated. The old distinction between Left and Right is overshadowed by being either pro- or anti-European. The Conservatives are clearly the party of the Right and Labour the party of the Left, but each is internally divided in its attitude towards Brexit.

This complicates the Brexit negotiations immensely and makes it difficult for Britain to decide its position towards Europe and even more difficult to modify it.

Brexit has also split British politics between young and old. Even though I am 87, I think a lot about young people who will live in a future I will never see. People under 35 voted overwhelmingly Remain and it was only over 55 that a majority of voters supported Brexit.

Old voters have overruled young voters who will have to live with the consequences of Brexit for decades ahead. This is aggravating the disillusionment with democracy among young people. It also raises the prospect that Britain will eventually want to rejoin the EU.

The doors of Europe may be open in the future, but if Britain leaves now it will never be able to rejoin the EU on the same favourable terms.

Since Brexit is a lose-lose proposition, it follows that a parliamentary vote to stop Brexit would be its opposite.

But a mere reversal of the 52:48 majority for Brexit is not enough. The majority for staying would have to be significantly larger to convince Europe that Britain’s attitude towards Europe has fundamentally changed and its decision deserves to be taken seriously.

The trend is moving in the right direction. The question is how its momentum can be accelerated so that it reaches a tipping point in the next six to nine months.

There is a chicken-or-egg problem: the electorate needs to push their MPs to give them the courage to rebel against the party leadership, and the electorate needs to be motivated not just to vote but to take an active role in politics.

Best For Britain seeks to break the logjam by bringing together all the various forces that are united by their aspiration for Britain to remain part of Europe. It has my wholehearted support.