"GOING on a march never changed anything.” You may have heard this joyless phrase in your life before – sailing out from the corner of a pub or family gathering, as you recruit for the next major date in the calendar.

The All Under One Banner (or AUOB) demonstration, for “everyone who desires an independent Scottish nation”, has just announced its date and location (it’s May 5, Kelvingrove Park in Glasgow, marching at 11.30am from there to George Square).

READ MORE: Scotland brand campaigners meet MP Wishart

So I thought it might be timely to find some substantive answers to those grumpies at the back of the room. In this age of protest, there is no shortage of research to draw on.

The first complaint to deal with is that “a demonstration doesn’t change what the politicians do at all”. What’s usually cited are the globally-organised protests against the Iraq War – many millions across scores of cities in 2003 – which didn’t prevent one single bombing run on Baghdad.

The Women’s March after Trump’s election was the biggest public protest in American history. But on the Monday after, the administration just kept on administrating.

READ MORE: Doing it OURselves is the way forward for Yes DIY

There are short-term and long-term rejoinders to this. In the here and now, the impact that marching feet has on politicians really depends on the level of togetherness and organisation amongst organisers.

In this week, 50 years since the assassination of Martin Luther King, many are going back to the stunning policy victories that the mass actions of the Civil Rights movement achieved. They reversed school segregation, public-transit segregation, interstate-bus segregation, restaurant segregation, poll taxes, employment discrimination and much more. What can we learn?

One obvious thing – that steady, deliberate, long-term organisation, which builds relationships and patiently waits for the right moment to go big, is key. When Rosa Parks took her place in the segregated seats of the Montgomery bus, she had been carefully selected to do so, after many prior rehearsals of what the New Yorker calls “a piece of public theatre”.

It’s not clear when the indy movement’s “big moment” is coming. But you can definitely see the rehearsals happening. Hope Over Fear takes over George Square and has YesBikers thundering round it. Hands Off Our Parliament puts a symbolic human chain around Holyrood.

Yet if you want policy change to come from protest, these events have to provide some kind of incentive to change from policy makers. They must manifest a “climate of opinion” that compels a response. And to do that, you must have some direct connection with the top-down.

MLK’s links with Washington insiders is often remarked upon. One amazing tale I picked up was about the 1963 March on Washington, where a very expensive and loud sound-system was sabotaged the day before the event. King called up no less than the attorney general Bobby Kennedy, who sent in the Army Signal Corps to fix it.

The All Under One Banner march has conducted a successful crowdfund for its event expenses (including PA). But one can also assume it has an ear (at least) in the heart of the SNP government. AUOB’s aim is to show that there is a continuing appetite for another bite at the independence cherry. So a successful march might well focus the minds of the indy parties’ leaderships.

Nicola Sturgeon and Patrick Harvie both face the question of whether they should exercise their mandates for a second referendum, before the end of the Brexit process. This decision could be heavily affected by forty or fifty thousand pairs of feet hitting the streets of Glasgow in May.

However, there is another route, identified by political scientists, to the short-term success of protests. And this perhaps contradicts the indy-centric focus of AUOB. Does the message have a resonance beyond the core supporters? What culture is it building, what values does it espouse?

The Civil Rights movement, notes the New York Times, combined a language of universal rights, the symbols of the black church, and an invocation of Gandhian non-violence. On the other side of the street, the US Tea Party movement in the 2000s explicitly tied its name to the inspirational founding moment of the Republic. Occupy Wall Street talked incessantly about “the 99%” (those living beyond the aggrandising elites). After they did, stories in the media about economic inequality trebled in number.

The stunning Catalonian public demonstrations score well on the ticklist of best protest practice. They have a properly staffed and funded organisation, and they have many feet in the halls of parliamentary power. But one also wonders whether it’s the way they’ve generalised their message that swells the numbers. They claim that this is a basic crisis of democracy, and now one of outright persecution, as much as a constitutional option.

Could part of AUOB’s message communicate better with those querulous No’s needed for a majority – particularly if it was phrased as a matter of democratic principle? Those longer in the tooth may roll their eyes at the propsect of the “democratic deficit” being taken off the shelf and dusted down.

But if these marches aren’t just about confirming the righteous identity of those attending, some thought has to be given as to who else can be invited to stand under the “One Banner” – other than the indy tribes.

That’s the current “conjuncture” (as the old lefties would say). For the long-term? The social scientists have been out with their graphs (particularly in the US). They are here to tell us that, in a slow-burn way, marching does affect policy.

A Harvard-Copenhagen study tells us that the larger the number of protesters on a particular issue in towns and cities, the more voters eventually turn out for the party that is seen to represent that issue. For example, for every additional attendee at a Tea Party event, it generated between 7 and 14 additional votes for a Republican candidate.

Why? They were motivated deeply by their rally experience, and thus remembered to show up on election day. Think of the party leadership of the SNP and the Scottish Greens reading this. They should be directly invested in the success of AUOB, who aim to double their attendance from 18,000 last year. Turns out there’s turn-out beneath them there placards.

There’s also some basic human resources to be taken from an indy march, too (and this is my personal list). The thrill of taking over car-free streets, with people who are idealistic citizens, not anxious consumers. The enjoyable creativity of fellow activists – the slogans, the costumes, the bands – as well as the simplicity of the Saltire and the Lion Rampant.

And in these choking, murky times, just the physical feeling of a clear commitment – that you haven’t ignored the challenge, or slipped into snarky cynicism (or weary despair).

Who knows what a great march will achieve? But even to excite the cells and re-ignite your hope, they are worth it. See you there, May 5.

If you’d like to contribute to AUOB’s crowdfunder, please visit www.crowdfunder.co.uk/2018s-auob-marches-for-independence/