London's longest run is back on Saturday, 9th May 2026. The London 100 is an urban 100K ultramarathon, with 25K and 50K options, enjoyed by 156 endurance enthusiasts for the first time last year. Organised by Participation Sport, with the special expertise of partners Camino Ultra, this unique event is the longest race held in the capital.

The race stands apart thanks to its course design. Four distinct 25K routes start from the superb indoor Run HQ at the Queen Mother Sports Centre, Pimlico, exploring hidden trails to the north, south, east and west of the city. Experience parts of London you never even knew existed and enjoy famous sights and landmarks of one of the world's greatest cities, in one long run.

The London 100K starts at 7:00am with a generous 17-hour time limit. Finish before midnight, and you will receive the coveted London 100 medal (pictured below). Finish in the top 100, and your name will be added to the London 100 roll of honour. Last year's London 100 winners were Pete Thomason (8:39:43) and Anna Brown (10:09:15), who was seventh overall. There were 79 finishers inside the cut-off time.

The inaugural 50K champions were Eddie Caviezel Cox (4:44:50) and the overall runner-up Zara Vermuelen (4:50:54) after a close battle with third overall Alicia Ellison (4:51:31). And at the 25K distance there was an outright female winner, Isobel Grad (2:08:22), from a rather gentlemanly Ben Alun-Jones (2:08:22), with 0.78 of a second the official winning margin!

One of the key elements of the London 100 is accessibility. The Central London location is easily accessible by public transport. With options from 25K to 100K, there is a distance to suit all abilities and levels of experience. Well-stocked checkpoints are positioned at the start and middle of each 25K loop to keep you energised and refreshed.

For full details and to enter London 100, click here.

Photo credit Derrick Wess for London 100 on Facebook