Meanwhile, Jeremy Corbyn has been busier. After all, he’s got a raft of new policies to promote – drawn up just before the big announcement – and team JC has a ‘Let Corbyn be Corbyn’ strategy…. so he’s officially allowed to be himself. This can make for compulsive viewing and I was up with the political nerds to catch him on Marr the other Sunday morning. He didn’t disappoint.

In a wide-ranging interview we learned that Jeremy is relatively unperturbed by the pressures of the highest office in the land. In fact, he seems carefree andrelaxed. However, this might be because he knows full well he’ll never be Prime Minister

An example came when JC was asked by Marr about that first, horrible task as PM,when the man from theAdmiralty taps you on the shoulder and you have to write those letters to submarine commanders patrolling the North Atlantic outlining what they should do if the UK has been wiped out by a nuclear strike. Those Letters of Last Resort are a chilling reminder of the responsibilities of a British leader. Effectively, you are a voice from beyond the grave, instructing commanders whether to fire back, killing millions more, or surrender to whatever is left of the world.

So what would Jeremy write? The response wasn’t so much an answer as a breezy ramble that managed to cast doubt over agreed party policy before moving on to a half-hearted analysis of the underlying causes of geopolitical tensions in Korea and Syria. He appeared to suggest that rather than a simple ‘fire all weapons/meekly surrender’ letter he’d seek to engage the officials in a conversation about how political solutions were always the answer. I’m sure at one point, when pressed, he said the commanders would just have to follow orders – obviously not fully realising that it would be him giving them. It’s more evidence that Corbyn is almost touchingly incapable of the binary answers that are demanded in modern politics. The trouble is that letting Jeremy be Jeremy is what makes him spectacularly vulnerable on questions of leadership.

I didn’t think the>Marr interview was a complete disaster – certainly not deserving of the Daily Mail’s description as a “car crash”. He performed relatively well on the domestic front. After being widely mocked for suggesting four extra bank holidays he came back well, arguing effectively that consumer spending on national days off probably outweighs any loss to the economy. He could also have argued that other countries with more public holidays – for example, France and Germany – far outpace the UK in terms of productivity. When it comes to increasing our economic output, the secret is to work smarter, not harder.

But, like several of his shadow cabinet colleagues, Corbyn doesn’t appear to be briefed enough to be able to make killer points or change the direction of interviews. The basics are there. But there’s no policy detail below the surface. It gives the impression of a man who just isn’t serious about high office, something that can be exploited ruthlessly by political opponents.