Heat by day, darkness by night
One hundred kilometres beside the Thames, completed continuously through a 33°C heatwave and a long night on the trail.
Putney Bridge to the first checkpoint
I set off from Putney Bridge at 7am on Saturday 9 September 2023. The early air was still fresh and the clear blue sky made for a calm beginning as the route followed the Thames through Barnes.
At 10.20am, after roughly 15 kilometres, I reached the first pit stop. It was an important opportunity to eat, refill my water and prepare for the heat that was already building.
Into the heatwave
I reached Kingston upon Thames around midday and passed the 25km marker at approximately 12.30pm. By then the sun was intense. The temperature eventually climbed to 33°C, turning what might otherwise have been a pleasant riverside walk into a serious test of hydration, pacing and concentration.
The route continued past Hampton Court Palace and onwards through Walton-on-Thames and Staines-upon-Thames. Historic landmarks, boats and the changing river scenery provided welcome distractions, while shaded stretches offered brief relief from the heat. By 4.30pm, I had completed 40 kilometres.
Halfway—and a warning
I reached the halfway point at Runnymede at 6.40pm, but I was feeling unwell. After speaking to the medical team, I discovered that I had taken too many hydration tablets. Their advice was simple: rest and drink plenty of plain water.
An hour's rest and a small meal helped me recover. It was a valuable reminder that hydration is about balance; more electrolytes are not automatically better, even during extreme heat.
Through the night
As darkness fell, participants paired up for safety. I teamed up with Monic and we continued by headtorch through woodland marked by glow sticks. Exposed tree roots and uneven ground demanded constant attention, while tiredness made every obstacle feel larger.
Working together helped us stay safe and keep moving. When we emerged from the woods at around 10.20pm, Windsor Castle appeared illuminated in the distance—a memorable and much-needed lift after hours on the trail.
The night became the hardest part of the challenge. Aching feet, heavy legs and deep fatigue slowed progress. At around 2am, we reached another rest stop in a hall. Some walkers lay on the floor while others sat quietly, everyone gathering enough strength to continue towards Henley.
The final kilometre
By 9.45am on Sunday, I had completed 99 kilometres. Only one remained, although on exhausted legs it felt considerably farther. Monic and I made our way through Henley feeling hot, sore and irritable, until the finish line finally appeared just 100 metres ahead.
At 10.11am—27 hours and 11 minutes after leaving Putney Bridge—I crossed the finish line. The relief and joy were overwhelming. With a medal around my neck and a glass of bubbly in my hand, it was time for photographs with Monic and her lovely family.
The challenge was complete, although the recovery journey began immediately. Even the walk to the railway station felt like another very long mile on aching, stiff legs. Returning to London and my hotel brought the welcome prospect of rest—and no further kilometre markers.
What the challenge taught me
This was my toughest endurance challenge to that point. It reinforced the importance of steady pacing, sensible hydration, mental resilience and the support of others. The heat, darkness and fatigue tested every reserve, but crossing the finish line proved that careful preparation and determination can carry you much farther than expected.
