Not really my main area but this caught my eye. I've seen a couple of reports from up near Epping and the old GER lines that cut through the forest and they do seem to cluster around old trackbeds and cuttings. Makes you wonder if its the geography rather than the railway itself - like these routes were often cut through older woodland that hadn't been touched for a long time before the navvies went through.
Could also just be survivorship bias, people walking old railway paths are already in isolated wooded areas at dusk so of course thats where encounters happen. But the specific point about OLD lines is interesting, a lot of teh pre-Beeching routes have been completely reclaimed by nature now so basically function as wildlife corridors.
Anyone got a proper map overlay of UK sighting reports vs disused lines? Would be genuinely interesting to look at the data properly rather than just vibes.