So the Greeks have voted no, China’s stock market is in turmoil and Unite is backing Jeremy Corbyn to become the next Labour leader. We can’t do much about the first two major events. So let’s take a look at the lesser one.

Jeremy Corbyn gets backing of Unite in Labour leadership race Read more

The first thing to say is that anything could happen under the revised leadership election rules devised by former party general secretary, Ray Collins, and endorsed by Ed Miliband. Here’s a simple guide.

What it doesn’t say is what the acting leader, Harriet Harman, said in May, namely that any supporter could register to vote for £3 and help pick the leader. Very democratic and all that, but is it wise?

In conversation the other evening, a leftwing chum said: “I’m not a Labour member (of course not), but I’m paying the £3 to back Jeremy.” At his side, a colleague mildly remarked: “Yes, some of my Tory friends plan to do that too.”

Both are gaming the system from different perspectives. Sensible people assure me it will only amount to a few thousand votes, but we can all remember that Ed beat brother David by a very tight margin (and Unite’s help) in 2010. The Telegraph has got excited.

The second thing to say is that Corbyn is a lovely man.

Liz Kendall’s candidacy is the real surprise in this election. Andy Burnham and Yvette Cooper – one of them is still most likely to win – are the mainstream, professional machine politicians in the race. Both were fast-tracked ex-cabinet ministers. Burnham ran last time (and hasn’t stopped running since), Cooper wisely let her husband, Ed Balls, have first try.

But few, if any, suspected the scale of Kendall’s ambition, not least Burnham, whose health deputy she was. I’ve known her for years in various capacities as a campaigner and special adviser to senior women – Harman and Patricia Hewitt. I didn’t have a clue she would become the outspoken Blairite torchbearer.

We’ll talk about her another time. As things stand her courage in stepping out of line is unlikely to be rewarded. No Tory or leftie will pay £3 to help elect Liz. Corbyn is both much better known (he’s the MP on the demo with the beard and sandals) and better defined. What’s more he’s a charmer.

Most fair-minded people in politics like him as a human being, none of George Galloway’s preening (though many of their views are similar) or the other vices of high-minded and vain leftwing politicians (as Simon Hattenstone generously explains here. Simon obviously liked Jeremy, he catches him very well.

Does that mean he should be the next Labour leader? I’m afraid not. My suspicion, shared by others better informed than me, is that Unite’s leader, Len McClusky (I’m afraid I like him too) lost control of his executive, some of whose members think Len’s a bit moderate.

He wanted Corbyn to stand as the left’s candidate and several Labour MPs who won’t vote for him helped to get him on the finalists’ ballot paper – he got the necessary 35 votes (15% of MPs) at the 11th hour – to broaden the debate. Rightly so, it would be a duller contest without him. But that’s not the same as actively endorsing him for leader: the Unite executive must have got carried away.

Jeremy Corbyn's late nomination shakes up Labour leadership contest Read more

We’ll see what happens in the coming weeks before the special conference hears the result on 12 September. For my money the Greeks have provided quite enough envelope-stretching leftwing experimentation for one summer (we await Beijing’s next efforts to manage its stock market crisis) and a Corbyn win would be huge fun, but one doomed to end in tears.

I realise that sounds world-weary to some younger voters who are fed up with the wishy-washy, middle-of-road politics which have left us all with a lot of debt, the prospect of years of austerity and unacceptable levels of youth unemployment. They’re fed up with dull, they want more excitement, less caution and more radical options. I say: “It isn’t dull in Greece any more. Don’t knock dull.” It couldn’t be much worse? Don’t you believe it.

Even some older politicians, Corbyn included (at 66 he’s a bit younger than me), say they’re fed up with “Tory lite” and want to strike out in radical new directions: non-nuclear, anti-capitalist, green in all sorts of ways.

That’s fine too, though it underestimates the achievements of the Blair-Brown years for Labour’s more needy supporters, a failure which has crippled the party’s recovery since its defeat in 2010 and shows little sign of improving.

But if you want radical alternatives you have to have a road map people can understand and believe in if they’re going to vote for it. In their not-so-different ways Ukip and the SNP (only the latter have made the kind of electoral breakthrough Syriza managed in Greece) have an advantage over the Greens and the Labour left. Their remedies have the power of simplicity (national sovereignty is the answer) that complex Green or Corbyn agendas (they overlap) lack.

Assuming that Corbyn can’t win on 12 September (“I like him, but I won’t vote for him, we’d lose,” one Labour activist explained the other day), what is the likely impact of his candidacy? It’s surely what he wants it to be, namely to pull the mainstream duo – Cooper and Burnham – to the left and further isolate the Blairite Kendall as yesterday’s woman when she’s barely got started.

Is that helpful? I don’t think so following a severe election defeat like the one suffered by Miliband. Romantic Labour activists may feel vindicated, but should be wary of their own comfort zone which is not where elections are won.

Miliband’s manifesto was far from hard left, not remotely Syriza-lite, and his failure was partly personal – as it always is in politics. Yanis Varoufakis has just acknowledged the personal in resigning as Greece’s finance minister to help his colleagues negotiate their way back from the cliff.

The danger for the left is to be wedded nostalgically to big state solutions of the middle 20th century at a time when the world has moved on, driven by globalised markets and – at an ever faster pace – by the tech revolution.

Increasingly meritocratic and individualistic voters chafe against inherited privilege, here as well as in Greece. They want social justice combined with economic efficiency, a phrase coined by John Smith but adopted by Tony Blair. They want accountability too. They’re not persuaded that Unite or even nice Mr Corbyn can create the vehicle for its delivery.