Confront your ultimate endurance challenge at Run The Grim Reaper on the stunning Grimsthorpe Castle Estate in South Lincolnshire on May 23-24, 2026. This lapped trail event offers four formidable solo distances—100 miles, 70 miles, 40 miles, and a standalone 10-mile day or night race—alongside a 100-mile team relay, making it the perfect proving ground for both first-time ultra-runners and seasoned veterans. You'll tackle a scenic 10-mile loop featuring ancient woodland trails, quiet estate roads, limestone tracks, and a disused Victorian railway line, all with manageable elevation (550ft per lap) that encourages strong, consistent pacing. The atmosphere is renowned for its friendly, supportive vibe, created by local runners who understand exactly what competitors need for a successful and memorable race.
Based in front of the magnificent Grimsthorpe Castle, the event provides on-site camping, a well-stocked running shop, and hot food and drinks available throughout. With a generous 28-hour cut-off for the longest distances and mandatory kit checks for safety, it's designed to be challenging yet accessible. Whether you're aiming to complete your first ultra, bag a 100-mile buckle, or enjoy a spirited 10-mile trail race by day or headlamp, the Grim Reaper delivers a first-class experience. Entries are now open for this highly-rated Lincolnshire classic—secure your place and prepare to run the reaper.
Races Offered
10 Miles day
May 23, 2026
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Distance —
16.1K
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10 Miles night
May 23, 2026
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16.1K
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100 Miles relay
May 23, 2026
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Distance —
160.9K
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100 Miles solo
May 23, 2026
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Distance —
160.9K
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40 Miles relay
May 23, 2026
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64.4K
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40 Miles solo
May 23, 2026
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64.4K
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70 Miles solo
May 23, 2026
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112.7K
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2 days remaining
Weather History
These values represent the 3-year monthly averages for May in Grimsthorpe.
thermostatTemperature
8.5° / 17.0°
wb_sunnyFeels like
5.5° / 13.9°
light_mode
Avg sunshine hours
10h 25m
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Avg rainfall
1.7 mm
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Avg snowfall
—
air
Avg wind speed
13.6 km/h (Gentle breeze)
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Sweat loss rate
Low
terrain
Course conditions
Firm and slightly soft
sunny
Max UV Index
Moderate (4.2)
humidity_mid
Humidity
76.7%
wb_twilight
Sunrise
05:03
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Sunset
20:52
About Grimsthorpe
Learn more about the host city, Grimsthorpe.
Grimsthorpe is a hamlet in the South Kesteven district of Lincolnshire, England. It is situated on the A151 road, and 3 miles (5 km) north-west from Bourne. Grimsthorpe falls within the civil parish of Edenham, which is governed by Edenham Grimsthorpe Elsthorpe & Scottlethorpe Parish Council.
