Occasionally there is wisdom to be found chatting to strangers at a bar – particularly perhaps in Missouri.

Missouri used to have some of the toughest gun restrictions in the land. But in 2007, it started repealing them – making it one of the states with the most lax.

The Johns Hopkins Centre for Gun Policy and Research found in the first six years after Missouri repealed the requirement for comprehensive background checks and purchase permits, the gun homicide rate was 16 per cent higher than in six years before. During the same period, the national rate declined by 11 per cent. After controlling for poverty and other factors that could have an influence, it calculated the increase was 18 per cent.

My friend at the bar explained that attitudes towards guns – he owned three, though he said he was not a “gun fanatic” – were not based on logic but on emotion. Even things like demands for a ban of weapons such as the AR-15 style rifle are seen as the “thin end of the wedge”. “People think the government is going to take their guns and they just want to hold onto them.”

And yet he recognised the seemingly unstoppable wave when he said the students from Parkland might be disrupting old thinking and old attitudes. “Trump is going to have to listen,” said my friend, who voted for Independent Party candidate Gary Johnson.

Hundreds of thousands of people marched on Saturday to demand tougher gun laws, to put an end to the epidemic of gun violence in America that kills an estimated 91 people every day. Their passion and intelligence was remarkable.

Of course, lots of people have marched for lots of causes before and seen no action. And the student survivors and the national movement they’ve given momentum to face huge challenges, not least the power and influence of the NRA.

Paul McCartney attends March For Our Lives rally in Washington DC

If the nation was not willing or able to change the way it deals with guns after 2012, when 26 young children and teachers were slain at Sandy Hook Elementary School, when will it ever?

This time might be different because those pushing for change, are not just parents and teachers and activists, but actual survivors - teenagers who found themselves scrambling for their lives when they should have been studying. They are the post-Columbine generation for whom lockdowns and “active shooter” drills are as much a part of their educational experience as the high school prom.

This means they not only have the passion and anger of having lived through an atrocity, but they have age and voting power on their side. As one survivor from Parkland, Delaney Tarr, told the crowds in Washington: “Today we are marching, we are roaring. We know what we want and we know how to get it. And we’re not to wait any more”.

The very clear message to politicians at rallies in hundreds of cities was clear; act or be voted out.

March for Our Lives – in pictures Show all 13 1 /13 March for Our Lives – in pictures March for Our Lives – in pictures Demonstrators chant during the protest for gun legislation and school safety AP March for Our Lives – in pictures Trevon ‘Tre’ Bosley, 19, of Chicago, the brother of Terrell Bosley who was killed in 2006 in a case of mistaken identity, speaks during the rally AP March for Our Lives – in pictures Marjory Stoneman Douglas High School student Delaney Tarr speaks at the rally AFP/Getty March for Our Lives – in pictures Protestors line the streets in Washington Getty Images March for Our Lives – in pictures People arrive for the March For Our Lives rally against gun violence in Washington, DC AFP/Getty March for Our Lives – in pictures Protestors carrying placards in Washington AFP/Getty March for Our Lives – in pictures Protestors hold up placards in Washington AFP/Getty March for Our Lives – in pictures Schoolchildren wear targets ahead of the rally Getty March for Our Lives – in pictures Attendees congregate in preparation for the march Getty March for Our Lives – in pictures Students brought a host of innovative placards AFP/Getty March for Our Lives – in pictures The movement’s main demand is the banning of assault rifles Getty March for Our Lives – in pictures Since the Florida shooting, students have called for urgent gun reform AFP/Getty March for Our Lives – in pictures In the wake of the Florida attack, President Donald Trump called for teachers to be armed AFP/Getty

The students have also been very honest about why they – articulate, middle class and largely white – may have been listened to more than, say, people of colour who suffered from gun violence that has ravaged cities such as Chicago or Philadelphia. They even went to visit with survivors in those communities.

One of the Florida students, 17-year-old David Hogg had the courage and grace to urge his fellow students from Marjory Stoneman Douglas High School “to use our white privilege” to make sure all people who have died in gun violence can be heard.

He also spoke the crowds in DC. “To those who say we are too young, we say “No More”.”

Change sometimes comes in increments, sometimes in a flood. Donald Trump may realise the majority of the country wants him to act to introduce universal background checks, to ban magazines that carry more than ten rounds and assault-style weapons such as the AR-15 employed by the Parkland shooter in such ruinous fashion.

I asked my friend at the bar, what practical use such a weapon had. Could it be used for hunting? No, it was too powerful, he said. “It’d just tear the animal apart.” That is what one of those weapons did to the young people and their teachers in Parkland six weeks ago.