It was all very civilised, at least to start with. David Cameron gave a speech to an audience, that was so well-behaved that it was almost worrying, on why we should all be civil to each other. There were men in suits and even a woman in a large-brimmed straw hat. Everyone was polite. Indeed, everyone was more than polite. We were in political luvvieland here, which, since we were at the Royal Society for the Arts, seemed appropriate.

Matthew Taylor, who worked at No 10 until about 10 minutes ago, told us that he had just run the marathon then introduced Dave with possibly illegal levels of effusive civility. Dave responded by thanking Matthew for almost everything (I think he left out the weather). Dave had not run the marathon because he was having a barbecue in his back garden.

Phew, what a torture! I was already beginning to see the problem with civility: it takes such a long time to get to the point. Dave’s speech was, as you would expect, polite. At one point he was a bit rude about people who were rude but he didn’t dwell. “A civilised society is a civil society, the literal sense of being civil to one another,” he noted. I began to wonder if there was a secret contest to use civility in as many ways as possible. “Civility is not something you can measure.”

Hmmm. I can’t see why not. Anyway, we were about to put it all to a test. After his speech, Dave was off to deepest Essex, which (whisper it, for to say it without parentheses would be rude) is not famed for its civility. And we were going by Tube. To Essex! I blame global warming. Politicians on public transport is as sure a sign of climate change as the melting ice-cap.

It was a 20-stop journey. Dave whipped out his book (the new Ian McEwan, On Chesil Beach). Everyone on the Tube was very civil to him. It was almost as if they had read his speech.

When we got to Epping, a handsome woman hurried up to Dave. “Are you who I think you are?” she asked. He allowed that he was. “Good luck,” she cried, and gave my elbow a squeeze as well. “That was very civil,” mused Dave. He absent-mindedly picked up a piece of litter. Two men rushed up to say that Dave had eaten in their Indian restaurant. Dave posed for pictures. I began to wonder if this was reality or something called Civility — The Movie.

Next stop was The Box, a charity that exists to help pupils who have been excluded from school. Dave plopped down on the sofa to talk to five teenagers who looked a bit sullen. “I’m David and I’m leader of the Conservative Party,” said Dave, perhaps a touch too brightly.

The kids looked at him. One pulled up his white hoodie. Another examined his mobile phone. Dave asked lots of questions. The answers, when they came, were monosyllabic. Indeed, I think the fullest answer for some time was, “Nuffing”.

Dave ploughed on. He asked the white-hooded one (who was 15 and called Jack) if he had gone to a pupil referral unit. Jack grunted that he had.

“What was it like?” asked Dave. “S***,” said Jack, ducking his head.

Dave asked him to elaborate. “They were a bunch of knob-heads,” said Jack, almost brightly.

Dave moved swiftly on, as you do, when a blast of reality gets in the way of a perfectly civil message.

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