Thanks to excellent prior FKT entry I avoided any big missteps, also carried all my water (3l) and food (5 cereal bars!) with me so no stops needed. Quite warm but luckily no direct sun. It's a good route although the north half is far nicer than the south (as that's just a relentless slog along the river with many many detours inland to go round construction and private property). Started at 6am so not many people in the touristy bits and parks were open. The route parks are reassuring but not frequent enough or directional so don't really work for navigation. Most of it follows existing routes (canals, thames path, greenway) so not too tricky.
5h 26m 14s