The race first begun in 2009 and is the brainchild of Anthony Taylor, Dick Kearn and the Trail Running Association.
The race only runs every two years and has run three times now, with around a 30-40% finishing rate, this is despite the calibre of runner that step onto the start line.
I had the display on and ready but cannot remember how to start the track. I press all the buttons and even scan the group around me for similar watches. Nobody seems to have this model. With Lindley counting down for the start I give up and just start my runkeeper for now.
Once the track opens out to grass and the river bank I find my comfortable pace and settled into my run.
I am aiming to keep no quicker than 9-9:30min/mile for the first day and see how my body holds up. Sleep breaks when required later and hope my legs can keep it up for the entire journey...
I stay within seconds to the front runners which includes Andy Horsley, we chat about the recent South Downs and I double check the route with their map, as I dropped mine without realising after five miles...
First Lady Karen Hathaway is close behind us once reaching the borough of Reading. Looking strong she is adopting a run/walk strategy by the looks of it.
Near Wokingham at ten miles and passing familiar checkpoints from other events I spot Paul Ali, who works nearby, supporting and taking photos as we pass him. Always good to see another runner routing for us.
The sun is strong now and it is feeling very warm already. The temperature is to reach 25C and above in London. There is very little breeze along this section so I take an S!Cap and drink plenty of water, I am very thirsty, more so than usual.
There are a few water taps along the way, which can be hard to spot at first, I refill where I can and ask at the locks to be let across to the water tap. I am refilling my carry bottle every hour.
I enjoy the long stretch through Henley-On-Thames, taking in all the sights and activities from the local rowing clubs. So many are out training on the river in the stunning sunshine.
A shout out 'go Luke' when I run over one of the decking bridges into Henley. Which I later discover from text by Helen, that it was Susie Irvin, a mutual running friend of ours.
Once off the river bank and cutting through the estate grounds at Aston, meeting flocks of young Deer as I go.
This is a section I forgot about when running the Thames in the other direction.
Once reaching checkpoint one at Hurley, I am already topped up with water so just refuel from my supplies.
I tuck into my avocado, some olives and pack some cheese with me for later. I feel satisfied already and the breakfast of bulletproof coffee has kept me going until here. All I needed was a gulp of olive oil at 20 miles.
I'm aware of the time spent stopping and plan to stop longer at the later stages, so thank the team and carry on the pathway.
The sun is scorching and I can feel the heat through my cap on my head. Headache and the feeling of dizziness is usually a sign I am suffering heat stroke. Being so fair I've never coped too well under the hot sun in the summer months.