By LIAM THARME and GEORGE EDWARDS / THE ATHLETICWith 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 minutes 42.66 seconds, 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 3:43.16, once considered untouchable, was no longer.“I’m following the footsteps of the giants,” Kerr, who broke the record last Saturday in the London Diamond League, to
