For the crowd that didn't want the Games party to end, one last amazing day

The greatest show on earth, as it has become customary to call it, finally came to an end with the grandest lap of honour. Hundreds of thousands filled the streets, 20 deep in many places, on a windy, occasionally drizzly afternoon, for one last look at London's Olympic heroes.

More than 800 of them, very nearly every Olympic and Paralympic competitor, filled 21 floats that left from Mansion House in the City of London at lunchtime, and slowly made their way past St Paul's Cathedral and down the Strand.

Crowds poured into every conceivable inch of pavement space, packing the entrance to the Savoy Hotel. Trafalgar Square, so often the centre piece of such occasions, appeared as packed as it could conceivably be. "We were here in 2005, when we won the bid," said Christine Horton, who was there with her daughter Grace. "Well I was, she wasn't born. And now we're here again. I don't think anyone knew in 2005 it'd be like this. It's magical."

When Mo Farah arrived on the first of the floats, and placed his hands on his head to form what is now known the "Mobot", Christine, Grace and everyone else went more than a little bit crazy.

Lining the Mall as the parade came to its final stop outside Buckingham Palace were 1,500 Games Ambassadors, in their pink and purple uniforms, hundreds of whom signed away their summers to catch not even a glimpse of any sporting action, instead working at Heathrow and Gatwick airports.

The floats were led in by grinning police officers on horseback, Paralympic Games accreditations still hanging round their necks, who waved and joked with the crowd – a scene representative of the unique mood in the capital for the past six weeks. Ellie Simmonds waved at the crowds, as did Sarah Storey. Several athletes held up handmade signs reading "No, Thank YOU" and "You Made The Games".

The Brownlee brothers hung off the back of their float to pose for photographs, and Katherine Grainger, the 36-year-old rower who won silver in Sydney, Athens and Beijing, and finally gold in London, was failing to hold back tears.

With the full Olympic and Paralympic teams assembled on steps at the Queen Victoria Memorial, in front of an invited crowd of police, service personnel, G4S guards (thousands of whom have done a very good job this summer), Locog and British Olympic Association staff, David Cameron said: "Thank you to the athletes, you've given us a gold summer for British sport and you've made us all so proud. The whole country salutes your brilliance."

The last word fell to Mayor Boris Johnson, who, as has so often been the case this summer, rather stole the show. "You showed every child in this country that success is not just about talent and luck but about grit and guts and hard work and coming back," he said.

"And speaking as a spectator, you produced such paroxysms of tears and joy on the sofas of Britain that you probably not only inspired a generation but helped to create one as well. Above all you brought home the truth about us and about this country – that when we put our minds to it there is no limit to what Britain can achieve."

After a flypast from the Firefly, the gold painted plane that brought the flame to the UK from Athens four months ago, with the words "Thank You" newly painted on the undercarriage, the Red Arrows did their thing. As 800 ecstatic athletes celebrated in their Union Flag tracksuits, a couple of red white and blue ticker tape cannons went off, and that was it, the end.