It is the numbers that seize you by the throat. Amid the brass bands, the hacking jackets and the stalls purveying Purdey "shooting wear" and Pimm's comes the realisation that you are at the biggest sporting event in Britain.
The crowds for the Burghley Horse Trials, the flagship event of three-day eventing, were always big but they have never approached 170,000 as they will this weekend. If this really is an elitist sport, an accusation levelled at eventing every time it seeks funding, then the elite stretches further than we could possibly have imagined.
Those who jammed through its gates – paying on average £26 for yesterday's cross-country element – would no more think of themselves as revolutionaries than they would swap Horse and Hound for a copy of Socialist Worker. But in the wake of London 2012 those sports that were once smothered by football are finding their own place in this summer's watery sun.
You can precisely date the moment when football became the middle-class sport of choice: the night of 4 July, 1990 when Paul Gascoigne broke down to the sound of Luciano Pavarotti signing Nesssun Dorma and 18 million watched Chris Waddle blaze his penalty into the night skies of Turin.
At the previous major championship, the 1988 Euros in West Germany, the only nation that sent fewer fans than England was the Soviet Union, which had its own reasons for restricting travel. The London Olympics may prove to be a similar turning point.
Ticket sales took off the moment the British team tasted success at Greenwich and, yesterday, the chief executive of British eventing, Mike Etherington-Smith, had to do something he had never done before at Burghley. He queued – at eight in the morning.
It might have been very different. Three-day evening combines the disciplines of dressage, cross country and show-jumping at a circuit of country houses across England. The wettest summer for a century had washed out its first big event, Badminton, which was to have been virtually a jump-off to select the British team for the Olympics. The circuit moved to Chatsworth, which was also abandoned, before pitching up at a minor venue, Bramham in north Yorkshire.
However, in one sense the sport got lucky. Zara Phillips, the Queen's grand-daughter, finished third and was, surprisingly, selected for London 2012. There, she provided one of the iconic images of the Games, being presented with an Olympic medal by her mother.
Unlike Team GB's show-jumpers and dressage riders, the three-day eventers won silver rather than gold, but as Mary King, who was competing in her sixth Olympics, pointed out, their success came very early in the tournament when it seemed that in terms of medals the London Games might not be delivering.
Unlike rugby league, which drove itself deeper into its northern ghetto by abandoning the BBC for Sky and audiences that would get the producer of Antiques Roadshow the sack, Burghley and Badminton still have precious terrestrial television contracts. There are country house settings – this one is in Lincolnshire – and, most importantly, easily identifiable characters.
This is what made snooker such a success when David Attenborough, then the controller of BBC2, decided to screen it.
There was the old master, Ray Reardon; the rebel Alex Higgins; the joker, Dennis Taylor, and the young assassin in Steve Davis. The 1985 World Championship final between Davis and Taylor remains one of the most watched events in the history British sport.
Eventing should have no trouble in assembling a similar cast list for what next season may be turned into a proper circuit that will produce a British champion. The tall, angular figure of William Fox-Pitt, who is unquestionably a bit posh, is among the best horsemen in the world and should he win Badminton next May he will carry off $350,000 (£210,000) for having claimed Burghley, the Rolex Kentucky and Badminton in succession.
Then there is Oliver Townend, the brilliant, chipper milkman's son from Huddersfield. And the 51-year-old King, who has been known to serve journalists lemon drizzle cake and who on Imperial Cavalier paraded her medal through the jammed streets of Sidmouth. Then there is Zara, who as a member of the Royal Family gives eventing something snooker cannot match.
With its shopping village it is easy to dismiss Burghley as a Benidorm for the Countryside Alliance set, but these are tough, tough people. "Nobody gets anything on a plate," said Etherington-Smith. "No, not even Zara. Her father was a hard rider and the Princess, God, yes."
Emily Parker, a 22-year-old graduate of Nottingham University and one of the best young riders in Europe, has a choice between a career in estate management which would pay the mortgage and a career in equestrianism that might not. She is going with the horses.
A few years ago, Lucy Wiegersma, who was first reserve for the Olympics, won prize money totalling £100,000. She could have used it as a deposit for a house. Instead she spent it on a trailer that can carry seven horses and which, from April to October, acts as home.
"I can imagine eventing taking off," she said. "The sport has fabulous locations and a certain glamour factor. Bernie Ecclestone had to take Formula One by the short and curlies and drag it up. Perhaps we can do that with eventing... Not everyone owns a horse, but please don't dismiss us as a posh hobby. A lot of people have scraped and clawed their way to be here."