If I say ‘Gordon Brown/Piers Morgan interview’ the chances are it will trigger some kind of response, that a memory either of the event or of the coverage will come to mind.

It showed a more human side to GB than is normally on display, and therefore came as something of a surprise to people.

It took place some weeks ago. David Cameron’s ITV profile by Sir Trevor McDonald was broadcast less than two days ago, and yet this morning Fiona pointed out she could remember next to nothing about it.

The pre-screening hype focused mainly on DC’s wife Samantha, who was perfectly nice and said nice things about him as you would expect. But it is true you’d be hard pressed to say there were memorable moments. True also that despite the build-up, only 1.6 million tuned in, fewer than half the audience for GB/Piers.

I thought Cameron handled himself quite well with people, like the ones at the railway station ribbing him about expenses. But as I reflected on Fiona’s observation, I realised the problem was Cameron really does avoid talking about substance. He loves to talk process – ‘this is where George sits … Here is Katie, she does the diary … I like to run round there … I like to get home to my own bed at night.’ That kind of thing is inevitable in the style of programme this was, but for a full hour’s transmission, he should have insisted that he was able to talk at least in part about policy and substance.

I hear he was recently asked at a newspaper editorial board why he wanted to be PM, and he said ‘because I think I would be good at it.’ It is an answer, in common with the impression of the programme, that suggests politics and his political career are all about him, not the people he hopes will elect him. Say what you like about Gordon Brown, but nobody could claim he is not driven by big issues and big causes.

Cameon looked energetic and lively on the news last night as he addressed a group of young people, but there seemed nonetheless quite a disconnect between him and them, and not just the one who was shouting at him about being ‘the new boy.’ His immediate response was to shout that ‘this is the kind of campaigning you’re going to get from me, open meetings, live debate’ – in other words, another campaign process point, when he could have engaged on policy in a way to suggest relative inexperience was not the problem the young man felt it to be.

He is perfectly good at the process stuff. But his constant reference to it suggests a real weakness, which I think will become more apparent as the pressure mounts.

GB on Piers worked for GB because it showed a side of Gordon seen all too rarely. I think the problem for DC on Trevor is that it showed a side of him we have already seen too much. Rather than addressing his weakness – lack of substance – it exacerbated it.

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