I'm ridiculously proud of being a writer. When strangers ask me what my job is, I say "writer", very much in the manner of Matt Damon saying "Texas Ranger" in True Grit. They then inevitably spoil my moment with: "Written anything I might have read?" And I'm left to mutter: "I'll get my coat", very much in the manner of Mark Williams's socially gauche Brummie in The Fast Show.

This past 12 months, it's been different. For the last year, I've been able to answer with a modest smile: "Actually, I was the writer for the 2012 London Olympic Games opening ceremony." I use the full title just to make it last, adding coyly: "Maybe you saw it?"

The answer is usually a gushing description of where they watched it, who with, how they almost missed it because they were sure it was going to be rubbish, but then it started and it was great. And the whole two weeks were great and then the Paralympics were great, too. And what's Danny Boyle like, and that thing with the Queen and ...

Well, then it all goes a bit quiet and we wonder where the promise of those two weeks went and what exactly was the promise anyway? And will it ever come back? The feeling is particularly intense if the stranger turns out to have been one of the army of Olympic volunteers. Then it's as though we'd both been to Narnia together and woken up in the Trafford Centre and I sort of wish I hadn't said anything.

If I look back at the emails and texts I got that night and the next morning, it was as if people were expecting some kind of alteration in the nature of reality. Steve Coogan wrote to me that it was "like the emperor's new clothes in reverse ... it made irony and postmodernism feel tired and past its sell-by date". Russell T Davies, the man who saved television, told me: "It changed my idea of the possible."

Walking to Euston to catch the train home to Liverpool the next day, it felt as if Danny Boyle had excavated a shiny new London from under the ruins of the old one. I was so drunk with the power of it all that I came up with my own proposal for social change. I called it The Dangerous Conversation, and it was about using the Olympic Park as a space to talk through seemingly intractable problems. I'm still trying, but nothing much has yet come of it.

Did anything come of any of it? Is the East End more prosperous, more connected? Will West Ham make proper use of the stadium? Will the Olympic Park blossom into a glorious public space? Will the nation be any fitter? And, if not, then what was the point?

Culture secretary Maria Miller has in recent months suggested that there should be some criteria for measuring the "worth" of culture. She described British culture as "a commodity worth buying into". The trouble is, culture can be an enormously powerful vehicle for change, but it's a vehicle with no steering wheel. It's unpredictable.

You could easily argue that the Beatles played a crucial role in the winning of the cold war. But Lennon and McCartney never did a PowerPoint presentation with an extensive list of the aims and objectives. Culture designed to create specific change is called advertising. Even then, it's hard to control. There's the famous 50s advert for Strand cigarettes ("You're never alone with a Strand"), featuring a man in a raincoat under a streetlight. It didn't sell any cigarettes, but it did create a run on raincoats.

This is why in the days after the ceremony there was such a range of opinion about what it said. There were internet forums dedicated to proving that the whole thing was a secret masonic ritual in which the parachuting monarch was a reference to Isaiah chapter 14 ("I saw Satan fall like lightning"). The citation for one of the prizes it won thanked Danny for creating a "vision of a more just and caring society".

But the important thing about the opening ceremony – the thing that people were responding to – was that it wasn't a vision. It's not what it said that counted, it was what it was. The cast and crew was the size of a small market town, with Danny as its mayor. He created and led a new community – a kind of temporary Utopia. While in the rest of the nation, bankers and celebrities and footballers and G4S were being paid massive amounts of money for being rubbish, here were people being brilliant. Not for money, but for the hell of it, for London, for the joy of being excellent.

Tabloid journalists offered them money in exchange for spoilers and photographs. There was talk of getting them to sign secrecy contracts or hand over their phones but Danny decided to try asking nicely and it worked. They "kept the surprise".

A show on that scale is a kind of barium meal that illuminates the hidden circulatory system that moves goodwill, idealism and eccentricity around our society. That's the real challenge of art. As GK Chesterton put it: "We have all forgotten what we really are ... all that we call spirit and art and ecstasy only means that for one awful moment we remember that we forget." The opening ceremony revealed that we are a better, bolder nation – and much more of a nation – than we thought we were. But to lament one year on that not enough has changed – as if things were just going to change – is to miss the point. It was always: what are we going to do about it?

There's a terrible story about Eddie Braben, the late writer of The Morecambe and Wise Show, watching their greatest sketch, "Grieg's Piano Concerto by Grieg". Neither Morecambe nor Wise nor any member of the crew could keep a straight face. And all the time Braben sat there thinking: "I'm supposed to top this next week".

I suppose everyone involved in the ceremony must have had that feeling at some point. Danny had the good sense to have a film ready to go when he finished. I was only too eager to get back to writing a children's book, though I did also have thrill of helping Walk the Plank design another mass participation event – this time in Derry for the City of Culture.

Suttirat Anne Larlarb, who designed those beautiful dove bicycles, has recently moved out of film and into teaching. That was her move. The real question is how we as a nation are going to top it. Because as Orwell wrote in The Lion and the Unicorn: "Nothing ever stands still. We must add to our heritage or lose it, we must grow greater or grow less."