What do Trump and Corbyn have in common?

Corbyn leading Labour? Trump in the White House? Such a world is far-fetched, but their popularity is telling about politics on both sides of the pond. And just imagine a world where they succeed.

It's 2017. A Jaguar moves slowly along the tarmac, a Union Jack flag fluttering on the front wing, and the car comes to a halt under the cover of the North Portico entrance. It is April 2017, and the two US Marines on guard stand crisply to attention their white uniforms immaculate, while a man in a tweed jacket and open necked shirt gets out.

He has a scruffy beard and slightly gaunt face. Waiting to meet him hand outstretched, stands a man with an unruly but massively hair-sprayed mop of blond hair. In his lapel a Stars and Stripes pin - on the lapel of the man he is greeting, an anti-nuclear weapon badge.

It is the first meeting between the Right Honourable Jeremy Corbyn, on his first official visit to Washington as leader of her Majesty's Opposition (once a few minor visa issues had been sorted), and the 45th President of the United States, Donald Trump.

One of them is filthy rich and likes to brag about it. The other is not ever so keen on the rich. Boy is this going to be the start of a special relationship. Well I guess they can always discuss the cherry blossom, which looks particularly fetching this spring.

Ok. It's not going to happen. It is far fetched beyond belief. Plain silly. Now let's talk about the present.

The latest polls suggest that "the Donald" or "the Trumpster" - choose your moniker - is far and away the most popular of the Republican candidates, while Hillary Clinton's campaign seems to be bogged down in porridge.

And in Britain a YouGov poll has Jeremy Corbyn - he of every fashionable left-wing cause for all the years he has been in the UK Parliament - storming ahead of his beleaguered and slightly drab rivals.

Every time Trump says something outrageous, or pokes a rival in the eye, so his popularity goes up.

And for Labour Party activists who have never really liked the whole, tedious governing thing and being in power (far too compromising) Corbyn is perfect.

Let's bring back maintenance grants and get rid of student loans? Easy. We'll whack up corporation tax or hit the rich with massively higher personal taxes.

Stop those thieving Mexicans crossing the Rio Grande? Simple - we'll build a giant wall all along the border...and you know what else we'll do - we'll charge the Mexican government for building it (quite why the Mexican government would foot the bill no-one has quite explained, but hey).

It seems we are in the age of the politics of simplicity.

Though Trump and Corbyn are from different political planets, what they offer is reassurance to those who feel angry and alienated (and there are a lot of them out there).

Critics would say what they are offering is simple solutions to thorny problems. But it is resonating. Nuance, detail and complexity seem to be so last year.

The people who are being attracted to these easy to grab hold of nostrums are not the mass of voters.

When elections come it seems that the electorate reaches an unhappy conclusion that life is difficult, and that they will reluctantly back the party that they think offer the best hope in difficult circumstances.

The Tories didn't win a majority because people were going to the polls saying 'I love these bunch of guys'.

Voters took a pragmatic view based on what they would be best for the economy, their jobs, and their families. The psychology seemed to be what will be the least worst, not what will take us to Nirvana.

All of which leaves the Republican Party and the Labour Party in that most dangerous of positions - doing something that makes the activists feel happy, but risks leaving the mass of voters behind.