There can’t be many people who’ve not heard of Rosa Parks, and of how she refused to move seats on that famous Montgomery bus way back in December 1955.

It was pivotal moment in the campaign for civil rights in America. Her arrest led to the definitive legal ruling that such segregation was illegal under the constitution, a ruling that started a cascade of legislation and demonstrated a model for change that the movement would use again and again. 

In 1999, Parks was awarded the Congressional Gold Medal and described by Congress as the “first lady of civil rights and the mother of the freedom movement”.

But we’re probably less familiar with the preceding story, the one that led up to that December day’s events 

In his recent and extremely readable book, Power to the People, Danny Sriskanarajah, former chief executive of Oxfam GB, relates some of that backstory. 

Of how Parks had been an activist for well over a decade and had already been part of multiple high-profile campaigns. Of how she had recently trained at the Highlander Folk School, a dedicated centre for activism in neighbouring Tennessee, and was just one of a number of NAACP activists who defied that same segregation law to get themselves arrested.

The NAACP leadership decided her case was the most promising one to put its full weight behind, both legally and as a rallying cry, and history shows her to have been an excellent choice.

None of that backstory should diminish what she catalysed and achieved, nor the resulting backlash she had to endure. But it does give a more rounded view of how systemic change comes about.

Often what appear to be individual incidents of great import are merely the most visible moments of a much longer process, involving much wider organisation, actively supported by a more deep-rooted movement, than we might initially appreciate.

Earlier this week I had the pleasure of hosting a public discussion with charity sector luminaries Juliet Bouverie and Mike Adamson, on the topic of how we bring about systemic change, in which Juliet shared her own anecdote.

Her organisation, the Stroke Association, had been running a big campaign to try to secure 24/7 access, nationwide, to a medical procedure called “thrombectomy”. 

They had put in a huge amount of effort, done the research, proven the benefits, invested in relationships and building their movement, which had been steadily increasing pressure and pushing at a whole range of doors, from hospital trusts up and down the country, to senior professionals across the healthcare landscape, to politicians of all parties.

None of which seemed to be opening for them.

Until the medical director of NHS England decided to prioritise it as his personal mission and committed to personally visit every single centre in England to ensure it happens.

Juliet says: “It was completely unexpected, something we never could have predicted, but it’s had a catalytic effect. It’s going to be a game-changer.”

Although she did concede that she had personally been on his back about it for three years!

But still, what she said is true. It’s not something that could have been predicted. But I doubt that in the summer of 1955 anyone could have predicted that one action by someone called Rosa Parks would change the game for the civil rights movement either.

But something would have.

Sooner or later, an arrest would have been engineered that allowed NAACP to force that same legal judgment, to provide a focus for their movement and an outlet for the pressure they’d built up over decades.

Every system has leverage points, where one small change can have a far greater impact. Where one rolling stone can catalyse a whole cascade of change.

But that one person, in the right place at the right time doing the right thing, will only become a leverage point if the pressure has been built, if the groundwork has been done, if our people in the room are already trained and prepared to see the door opening, and to have the courage and support they need to push through it. 

Just like Rosa Parks was.

We can never quite predict which door will open, which is why we have to push on them all.

And that takes commitment and resilience, investment in people and relationships, and the agility to shift our weight behind the opportunity the moment it appears.

But if we’re serious about social change, these are the models we need to learn from.

And if you’d like to join our next conversation, with Polly Neate and Kate Lee, the chief executives of Shelter and the Alzheimer's Society respectively, you’d be very welcome.

Martyn Drake is founder of the management consultancy firm Binley Drake Consulting