Hundred Hills 50km

The Hundred Hills 50km is two different 25 km loops through the Chiltern countryside, starting and finishing at Stonor Park near Henley-on-Thames. It is the first race of Centurion Running's year, and the flattest way into its calendar: 4,000 feet of climb across 50 km of ancient woodland, village lanes and the beech hangers above the Hambleden valley, out through Ibstone and Skirmett on the first loop and Hambleden and Bix on the second.

The race holds a 9-hour cutoff on a marked course with five aid stations, and it starts in two waves, at 8:45 a.m. and 9:00 a.m., with the same time limit for both. Only wave one is eligible for the overall men's and women's awards; age-group awards can be won from either. The field is 600 and there is no qualifying standard beyond a minimum age of 20. The race has run since 2023 and 2027 is the fifth edition.

Two 25 km loops from Stonor Park, Stonor, near Henley-on-Thames, both starting and finishing at the park. The first loop runs out to Ibstone and Skirmett before returning through Stonor at 14.5 miles; the second takes in Hambleden and Bix before the finish. 50 km with 4,000 feet of climb, five aid stations, 80 percent trail and 20 percent road, and a 9-hour cutoff from a wave start at 8:45 a.m. and 9:00 a.m. The course is marked.

Entry is first come, first served through Centurion Running for a field of 600, with a waiting list once entries fill. Entries for 2027 opened at 10:00 on 5 April 2026 and close on 5 March 2027. The fee is 80 pounds for UK Athletics members and 82 for unattached runners. There is no qualifying standard, and the race describes itself as suited to a first ultra or a step up to the organiser's longer events.