So it came off. Something of a triumph, I'd say
No-one could be sure what would happen, but a crowd of at least 30,000 of us gathered along the Thames Embankment, with only occasional glimpses of sunshine and enough hints of cold and damp to deter all but the hardiest of outdoor activists.
I've been to a fair few of these things before, and I can't off-hand think of a demonstration that was quite so peaceful and friendly, diverse and big - including even the Stop the War demonstrations when they began.
We pitched the NI banner (an innovation, this) between the National Union of Journalists and the giant purple balloons (another innovation, quite handy for lifting you up as you tramp along) of Unison, the pubic-sector union.
There was a big turn-out by trade unions from across the country, including Northern Ireland and Scotland. The NGOs and faith groups were less obvious, at least from the banners - but then they're not usually tooled-up for this sort of thing and instead provided flags: 'Put People First - Jobs, Justice, Climate'. The logo and artwork for Put People First were done by my colleague at the NI, Andy, and it was wonderful to see it everywhere.
There was a good deal of graceful, spirited flapping in the bitter wind, especially around the notorious wind tunnels made by Big Ben, Whitehall, Trafalgar Square, Piccadilly. This is what I like best about demonstrations. For once, people take over streets that otherwise are a choking tangle of arrogant traffic.
Come to think of it, joining demonstrations could be a tourist attraction in London, since you get a superior view. Two cheerful young women from France and Poland had seen the special NI supplement in The Big Issue and felt inspired to come along.
Even so, the march was the start of what I fully expect will eventually change many more people from mere spectators of the meltdown into active participants in something a good deal better.
What is this likely to be? Well, we had some difficulty coining slogans. 'What do we want?' We're thinking about it - and we laughed. 'When do we want it?' As soon as possible, if you don't mind.
Does that make us incoherent? In fact, as the current issue of the NI magazine suggests, there's a pretty convincing 'manifesto' for the future that's long been in the making. My colleague Vanessa Baird and I are currently putting together a book - due for publication in a few months - that will spell it out in more detail.
But, right now, and on this wonderful day, the issue was not so much who has the best slogans or manifestos as how to make the change. That means 'politics'; for example, replacing the notion of 'regulation' with that of 'democratic control', which is what regulation really means, rather than some sort of technical fix for mad markets. And that, in turn, means less of the competitive splitting of hairs, more of the co-operative contest of ideas.
Anyway, after tramping through the heart of London for three hours we arrived too late in Hyde Park to hear much of what were doubtless very stirring platform performances.
And then the rain - or rather, the ice - came down. My daughter and I headed for a Turkish snack-bar just off Oxford Street. Noticing the 'Put People First Flag' we still carried, they asked how the demonstration had gone. Business permitting, they promised to come next time.
Back home in Bristol, this morning I went to the local BBC to share six-and-a-half minutes of sub-prime TV time with an accountant and a sharp young executive from the 'ethical' Triodos Bank - which is prospering and even (surely not!) lending money, to sustainable and fair-trade projects. Not least, the executive pointed out, he still has a job.
I tried, in a trice, to present the case for maassive and urgent investment in sustainable activities, making useful rather than dangerous things. An evidently underwhelmed presenter said: 'But that doesn't make money.'
He had warned us beforehand that the audience tended to be 'elderly' (not unlike me) and we should therefore avoid jargon. This precluded me from discussing the meaning of money, or of making money with money without making anything else at all.
'Put People First' in Bristol may be gathering again soon, and I'll have to ask them what I should have said. It's too late now, I'm afraid, at least for the BBC, but how about you?
The mainstream media are still licking their lips at the prospect of violence as the G20 meeting on 2 April approaches. Together with the Metropolitan Police, they should really declare a vested interest in goading it on, thereby deterring people from joining the G20 Climate Camp in the City of London on Financial Fools' Day, next Wednesday 1 April.
With any luck, yesterday will encourage even more people to think otherwise.