Andrew Peters is limbering up next to the start line in the Olympic Stadium. With receding hair and a heart monitor strapped round his chest, the 50-year-old investor does not look like much of an Olympian. But today he will be ahead of the world's finest athletes – becoming one of the first ever to cross the finish line.
His pre-race regime was rigorous. Isotonic drinks or carb-loading were not enough for Mr Peters, who is relying on only the best nutritional preparation. "I had a few drinks last night," he admits. "About a bottle and a bit of wine. That's good for you, right?"
He's not hoping – luckily – to break any records. "I'll be chuffed to get around and if I can do it within the hour I'll be a happy man."
Mr Peters is one of 5,000 people chosen at random to take part in the National Lottery Olympic Park Run. It is the first time an Olympic stadium has held a race before the Games themselves and competition for a place in the race was fierce. More than 43,000 people entered the ballot to get the chance.
The day is being seen by organisers as a dummy run for the Games themselves, though the spectators, who number under 10,000 are not officially trying out the 80,000-seater stadium. Weeks before, there were already signs of anxiety that this event would test the park: the press were told to arrive three hours before in order to clear security, and instructed not to try to park in Stratford City. Come the day, the rows of airport-style security run by G4S are all manned and empty: the volunteer spectators sail through.
Lining up for the start of the race, the runners take the chance to gaze in bemusement at the ArcelorMittal Orbit, otherwise known as Anish Kapoor's £19m "hubble bubble". Dressed in red T-shirts with the slogan "We were the first to cross the Olympic finish line", even the least athletic-looking seem excited.
Mixed in among the amateurs are a few former Olympians, including Roger Black and Sally Gunnell – some looking in better condition than others. James Montague, 61, boxed for Ireland in the 1972 Munich Olympics, making it into the final 16. Now, one of his calves is wrapped in a crepe bandage and his moustache is greying.
"I won't be breaking any world records today," he chuckles, "but being here brings it all back. The atmosphere is just the same as 40 years ago. I can only imagine how good it's going to be in the summer."
As Princess Beatrice concludes her opening speech and the countdown finishes, the runners stream over the start line, heading off towards the basketball arena. Snaking for five miles around the Olympic Park, they do a loop of the velodrome, past the press centre, the water polo arena and the aquatics centre, until finally coming out through a tunnel into the stadium itself.
After around two miles, many are already walking. Rivals for Usain Bolt they certainly are not, but almost everyone is still smiling.
The first person to cross the finish line after 23 minutes 4 seconds is Stuart Bloor, 24, a wheelchair racer from Cheshire. "I never expected this," he says, his hands still shaking. "I only started training a year and a half ago, and it's my dream to get to the Paralympics."
Though the course is not an official Olympic length, the best long-distance runners in the world would probably complete it in around 21 minutes. So the crowd starts to cheer when the first runner emerges from the tunnel into the stadium after just over 24 minutes. Far ahead of many competitors, 26-year-old Tommy Davies, from Loughborough, finally finishes in a very respectable 25 minutes and 11 seconds.
Davies, who works as an administrator for British Triathlon and is a keen amateur, even manages to beat the Olympic record. His race is 0.2 seconds faster than Emil Voight's winning run at the 1908 Olympics in London, the last time five miles was a category in the competition.
Waving to the sparse crowd as he runs the final sprint through the stadium, Davies is clearly revelling in living out a sporting dream. Speaking to the crowds of waiting camera crews about his sprinting win at this event, he says: "I'll feel great watching the Games knowing I've crossed that line first today."
As the clock for the other runners ticks towards 45 minutes, the competitors crossing the line are looking increasingly exhausted, and the distribution rate of blue sick bags grows dramatically.
Maria Hendry, a 55-year-old dinner lady from Fauldhouse, West Lothian, staggers across the finish line after 57 minutes of – mostly – running. "I'm not going to lie. I had to walk two or three times on hills," she admits, "but it was so incredible to run into the stadium.
"I was quite tearful in the final stretch. When I was younger, I used to run in a running club. But then I stopped, got married and had children. To be here today is a dream come true."