Well I've never driven the Bridleway bit. I walked some of it a few years ago and it was pretty rutted, but as you say, notalot of places to roll unless doing something very wrong.
'course, it could be a simple accident, foot slips on clutch, or throttle if Auto, wheel's turned, you're suddenly up a bank and rolling .. In low box even at tickover a Landrover can potentially roll itself over very easily and quickly before stalling, and hitting the sides of, say, the Roych steps could lift one wheel enough to do so within a couple of feet of forward motion ...