A 50 km trail ultramarathon in the Chiltern Hills starting and finishing near Stonor with approximately 1,200 m of ascent. The route follows woodland trails, ridge paths and rural footpaths across the Area of Outstanding Natural Beauty, linking sections of the Chiltern Way and surrounding countryside. Elevation is accumulated through frequent short climbs and descents rather than extended mountain ascents. Surfaces vary between compact trail, chalk paths and softer ground after rain. The course is fully marked with aid stations positioned at intervals along the route.