A few miles later, into Nymans Woods, it clears up suddenly and swiftly. The forest floor blazes golden brown, a thick carpet of beech and oak leaves.
It's starting to feel like summer but the trees are still bare. Only the holly, ivy and moss provide shocks of green.
It's been mostly dry for a couple of weeks and the going is easy, There's little mud on the footpaths and much of the route is on metalled or gravelly bridleways. Through the village of Handcross, bisected by the six thundering lanes of the A23, then diving back into lush lanes, between green banks scattered with primroses.
Deepest Sussex, about as bucolic as you can get in the south east. At times you do feel quite far away from it all.
The sun is strong, the going is easy, and I'm covering ground fast.
Iron was worked in the Weald from prehistory to the 18th century. As the industry grew it needed more water. There are still many little reservoirs scattered through the folds of the land.
Lunch is taken sitting on a mossy bank by the bridleway watching the world come back to life.
It's getting hot and from here to Horsham the trail goes almost against the grain of the land. Up, over and down a succession of ridges...
...stalking a peacock butterfly, camera and hand, hoping it'll stay still long enough, but it doesn't...
...and on into St Leonard's Forest where the wood anenomes are at their peak...
A track runs dead straight along the broad crest of a ridge in the heart of the forest. Scots pine, birch and even heather thrive up here on the old heath. I really like it up here, the big skies seem closer somehow.
Horsham is near. There are dog walkers and a smattering of litter, then more houses, then a straight road by suburban houses and a convoluted walk around to the station main entrance guided by a friendly local. In an hour I'm back in London but spend another hour trapped on a bus snarled up in an angry funnel of traffic around Waterloo as a crane takes up half the road to send yet more glass and steel skywards.