Donald Trump is the nominee. This is a dark day for America

I am the man who last year walked past the launch of Donald Trump’s campaign launch in New York on the basis that it would obviously amount to nothing. It seemed to be nothing more than a bunch of crazy looking people wearing “Make America Great Again” t-shirts. I should have stopped, gone in and watched, but didn’t. On this, my predictive powers are up there with all those smart people who advised banks and hedge funds that Brexit would never happen.

Now, here is “the Donald”, confirmed as the Republican nominee for President of the United States. In Cleveland, the party of Ronald Reagan and Abraham Lincoln has been through the formalities and completed its shameful act.

Since that day in New York – when I walked on past Trump Tower and went to the Frick museum instead – I have heard some people whose views I otherwise respect tell me that I have too much of a downer on Trump. He’s a little loud, they say, but the voters in the US and elsewhere are mad as hell and they’re not going to take it any more, as the fictional Howard Beale (a news anchor driven demented) tells his viewers in the 1976 classic film Network. Trump’s a natural chief executive and he knows how to run a business, they say (I question that assertion, but that’s for another time.) The constitution has safeguards, it is said. They’ll impeach him within six months, won’t they? What’s the worst he can do until then? He’s not going to start a nuclear war, or at least not on purpose.

That is the sound of otherwise smart people trying to post-rationalise an epoch-defining disaster for the centre-right in the US and for conservatism more broadly. Some on the intelligent Right want to come to an accommodation with the thought of a Trump presidency, because they think it might happen and want to be ready. Others think he might shake things up a bit and they like his robust agenda that may appeal to disaffected blue-collar Democrats.

Those making such allowances for him are indulging a dangerous fantasy. Trump is not only a cartoon character who is ill-equipped for the practical demands of office. He is a narcissistic know-nothing whose utterances on women and anyone who disagrees with him should disqualify him from the nomination.

But it is even worse than that. We have become wary of 1930s comparisons, because invoking Hitler or the other fascist dictators of that era usually turns out be an exaggeration. Occasionally, though, the parallel is apt. Populist anger is at boiling point, and if there is another economic crisis or a large-scale terrorist attack on US soil then Trump looks capable of doing just about anything, no matter how unhinged, in response.

Ultimately, there is much in what the great satirist P.J. O’Rourke said when asked about this. How could he – a Reaganite Republican – possibly consider voting for Hillary Clinton this year? She is wrong, he said, about everything, but unlike Trump she is at least wrong within normal parameters.

Like the tens of millions watching outside the US, I have no vote and would not presume to advise American friends what they should do. Nonetheless, I am filled with an overwhelming sadness about the condition of a country which – like many Britons – I hugely like and admire. One of its great parties has nominated as its candidate for President a tin-pot trainee demagogue who is a danger to us all. This is a dark day for America, and for friends of America.