Centurion Running

Centurion Running put on the best-known 100 milers in England — the South Downs Way, the North Downs Way, the Thames Path and the Autumn 100 — along with a set of 50s and 50ks on the same trails. Their model is the opposite of the self-navigated school: courses are fully marked, aid stations are frequent and well stocked, and the cut-offs are generous enough that a determined walker can finish. That is deliberate — a first hundred is meant to be finishable here. Most races require a qualifying result before you can enter, and the popular ones fill within hours of opening. There is a Grand Slam over the four 100s and another over the 50s.