The alternatives were horrifying, so I drove to a car park at the edge of Cookham. I headed off down the public footpath, following the top of Winter Hill golf course. The path tracks the Maidenhead / Bourne End railway line. The path dips under the railway, and out around the base of Winter Hill (a sharp hill, ending in a Thames flood meadow). I doubled back across Cock Marsh to the Thames at the Bourne End railway bridge (which I note is also a pedestrain bridge). I followed the Thames back towards Cookham, turned right (alongside the sewage works, although I didn't know it at the time), up the hill, back to the car park, and then home. 2.3 m, ~75mins, including photo stops. Maybe I can link to the My Map in google...