Boyd Tonkin: I knew it would work when I saw Doreen Lawrence carrying the Olympic flag

Collective will, collective passion, can spread like a contagion. How far can we separate the true believers in the Olympic and Paralympic flames from the millions who felt in some way warmed by their heat? We need not bother. The delight, the enjoyment, the solidarity, has caught on like brushfire. It crackles as I write as, along the Strand, thick crowds greet athletes, volunteers and staff as the floats roll by in the closing parade. It is impossible to resist.

What we have seen is a culture of inclusion, of active acceptance rather than passive tolerance. A Mo Farah or an Ellie Simmonds, a Jessica Ennis or a Sarah Storey, no longer has to knock on closed doors in the hope of finding a marginal role within a pre-existing narrative of community. They make and tell that story: not as bit-players, but as leading parts. Danny Boyle's opening ceremony struck this note with the big, warm hug of its historical surrealism. Then, as life – or sport – ratified art, events from pool to track to velodrome confirmed it time and time again. This was for everyone.

I watched Boyle's impishly intelligent extravaganza in a hotel lobby in a genteel spa town in central Italy, before flying home. Many people will have memories of the single moment when they first thought: this will be all right; this is going to work. For me it came with an astonishing lurch of the heart, when I realised that among those carrying the Olympic flag was Doreen Lawrence. In a way that had no precedent, the country that I lived in – or perhaps the country I wanted to live in – was fully represented, honoured, understood, with the worst it could do acknowledged with the best.

No one has abolished double-dip recession with an Olympic-branded magic wand. Austerity chancellor George Osborne – in that historic proof that the Games goodwill did not make the happy crowds take leave of their senses – endured the stadium boos. Those Paralympian overachievers still face deep cuts.

Still, from the time in May that the Olympic flame began to pass from town to town through always-cheerful crowds, it became clear to any unbigoted observer that most people both wanted to enjoy the show, and were prepared to make it succeed. Moreover, as soon as the competition kicked off, we could see the somewhat camp, music-hall patriotism that cheered along the British athletes left room for a grudge-free appreciation of everyone else's talent and success. Yet on left and right alike, the culture-war declared by the British pundit class on their fellow-citizens – an ugly blend of snobbery, prejudice and downright ignorance – had closed minds and skewed perceptions, chronically underestimating the people's power to make these Games.

Hence the G4S fiasco became not a glitch but a defining symptom of looming catastrophe. From Martin Amis to David Starkey, this lip-curling scorn for the messy, hopeful actuality of British life has ceased to operate as any kind of positive stimulus to reform. Rather, it serves instead as a pillar of the deeply reactionary ideology of "declinism". Could the Games kill off such declinism for good? We should hope so.