With a fist pump as he crossed the line, Josh Kerr cashed in a check that he had spent eight months writing.The clock stopped at 3:42.66s and the London crowd erupted.A Briton, on home soil, had just taken down a world record from 1999. Hicham El Guerrouj’s time of 3:43.16s, once considered untouchable, was no longer.“I’m following the footsteps of the giants,” Kerr told reporters afterwards, referencing the fact he is the seventh British man to hold the mile world record, 72 years after Roger Bannister broke the four-minute barrier for the first time.This performance was the product of Kerr’s self-branded Project 222 — the number of seconds that go into 3:42. He pitched it to Brooks, his sponsor, last November, just four weeks after hobbling to the finish in the 1,500m World Championship final because of a calf injury.“The body is electric right now,” said Kerr. “I felt pretty incredible. My legs felt good, my mind was ready, but it’s been a long journey.”Kerr does not so much race middle-distance events as play poker within them, always running in sunglasses and being one of the smartest at showing his hand late and covering moves by others. By the same analogy, with this project, he went all-in on a blind hand — and won.The split of 3:27.62s at 1,500m was even quicker than Kerr’s British record run, which earned him silver at the 2024 Paris Olympics, and he was near-perfect when cutting the race in half. He passed 800 metres in 1:51.1s, then pacemaker number one Brandon Kidder dropped out, and then Kerry clocked the second 809m in 1:51.6s. “I knew I had it in the first 400m because my pacemakers did an incredible job,” he said.The preparation for this race was intense, and needed to be for the 2.68s improvement the 28-year-old produced. But what made it a reality?Brooks crafted Kerr a bespoke spike, made for his mechanics and to run 55-second laps on repeat, in addition to an aerodynamically tested speed suit. The process of creating his footwear involved VO2-max (how much oxygen your body can use during intense exercise) and perception testing, plus a visit to a bespoke facility to run on a treadmill in the race-day spikes.Kerr spoke about the “sacrifice” his team-mates and his family had made. For the past five weeks, his parents have lived with him at altitude in Albuquerque, New Mexico, to enable Kerr to train on a track at 1,626m (5,335ft) above sea level, with his mother Jill providing physiotherapy.“The mantra… was that we’re not chasing world records, we’re creating the conditions where world records become inevitable,” Kerr said.That meant 70-mile weeks and running as many 55-second laps as possible. One of the key sessions was a 4 x 800m workout, with the third and fourth reps at 1:50, in which Kerr tested spike prototypes.Nothing was left to chance in Kerr’s world record attempt (Henry Nicholls / AFP via Getty Images)Fellow Brooks Beasts athlete Kidder played rabbit in the race, just like he had in training. He hoped to get to 1,000m rather than 800m, and suffered because of a slightly fast opening lap (54.75s).“I knew Josh was really fit, so I felt a little bit of pressure to not mess things up,” he said afterwards. “Josh just looked so good. I was like, ‘If he wants to squeeze, I don’t want to get in the way.’ (It’s) such a cool moment. I’ve known the guy for years. He’s a gamer.”Their relationship goes back to 2017, when Kidder was already running for Brooks and they recruited Kerr, a three-time NCAA champion, from the University of New Mexico.Kerr first shared his desire to break the world record in December and asked if Kidder wanted to be involved. Little convincing was needed.Zan Rudolf also stepped in as a late replacement after another pacer dropped out. He and Kerr did one ‘workout’ together the day before the race — 300m, 200m and 100m at target pace — as Rudolf only arrived in mid-week, having been in Budapest for other pacemaking duties. The Slovenian went three-tenths of a second quicker than his own national record to lead Kerr through the kilometer mark in 2:18.7s, also dropping out short (he planned to go to 1,200m).Coach Danny Mackey, who has worked with Kerr since he turned professional in 2018, was watching from the stands. He said he was “a little worried” to have the Scot running alone that early but had complete faith in his athlete.“That was the most elated I’ve ever been,” said Mackey afterwards. “In the lead-up to the race, there have been cameras and attention on us, something we just aren’t used to. We all knew he could do it. I told him I love him.”Kerr, however, relished the high-pressure moment, which is partly why he publicised his record-breaking attempt back in March. “He’s a rare person like that, but he’s still human,” Mackey said.The coach’s one complaint? That it was only 3:42.66s. “Based on a couple of his workouts, if he had better weather, I think there’s another second there,” mused Mackey.Mild crosswinds meant conditions were not perfect. They knew that coming in, and Kerr was happy to roll the dice to do this in front of a home crowd, whereas Mackey would have staged it in Monaco or California.He and Mackey work as a coach-athlete pairing because of their differences in opinion. “I’m a little bit of a bodyguard,” said Mackey.An 800m personal best for Kerr in mid-May confirmed what Mackey and the team knew in training: his top-end speed was better than ever, and he had rediscovered the “final form” that Kidder saw in 2025, but a calf injury prevented it from fully flourishing. This was not, as Kerr put it in the pre-race press conference, his “first time” being in mile world-record shape; rather, the “first moment” he could dedicate a season to target it.Kidder paced Kerr in a 1,200m time trial at altitude at the start of July. They simulated their shakeout run and physio treatment to mimic race day. “(We were) working on every detail that we possibly could to come to London, an international trip, and (make it) like a practice.”Kerr finished the time trial in 2:42.45s, more than five seconds quicker than El Guerrouj’s split in his world record run. “I was like ‘Oh man, let’s line it up tomorrow, he’s got this in the bag,’” Kidder remembers. Kidder was already convinced, having seen Kerr finish a workout totalling 4,000m at world-record speed — four sets of 200m, 600m, 200m.It’s easy to see now why Kerr and the whole team were so full of belief. “It won’t look like a chase,” he insisted pre-race, preferring the word “pursuit” instead.Britain’s Josh Kerr set a new world record in front of his home crowd in London (Harry Murphy/Getty Images)Kerr held pace throughout the final lap, pulling away from Yared Nuguse (who finished second in 3:45.69s). The American had been close behind when they hit the bell, but faded to finish a little over three seconds back.“It was just deafening, that last 200m,” Nuguse said afterwards. “I’ve never heard a stadium that loud.”If one moment captures things perfectly, it was the evening before race day. Instead of dissecting possible outcomes or making last-minute adjustments, Kerr and co were at the warm-up track. He was a stand-in videographer as Brooks staff — including assistant coach Julian Florez and chef Jamil Austin — took part in a mile race of their own.They ran relay legs of 200m each to see if they could beat Kerr: a finish time of 3:55 was 13 seconds slower than the Scotsman would run the next day.“If it was just me, he wouldn’t do it,” Mackey said. “We are all really tight, and that creates an atmosphere for Josh to thrive.”