Last Saturday I ran in the Country to Capital 45 mile ultra.
This starts in Wendover and goes through Chesham to Denham on footpaths before following the Grand Union Canal to the finish at Little Venice.
You were expected to navigate so local knowledge was a big advantage. I was 1st lady in 6hrs 49mins 30secs.
If anyone is interested in running it next year I can let them know the route as I have the map!