If you are considering walking this route yourself, please see my disclaimer. You may also like to see these notes about the maps and GPX files.
The bridleway immediately passed a bungalow on the right, and continued for several hundred yards between old hedgerows either side. It eventually emerged onto the top of Bison Hill, where I followed a path going half-right through the grass, descending slightly. At a path junction in the grass I turned (or forked) left (instead of continuing to a gate) then after 20 or 30 yards turned right onto a crossing path which took me to a metal kissing-gate (another path was a short way to my left, close to a road). Through the gate a path continued with the hillside soon sloping down to my left. I soon reached a faint fork just before two trees, and I was surprised that the right fork was far more obvious than the left fork as its always previously been the other way round. I found out why, because when I took the left fork it was eventually blocked by thorny bushes. I had to go a little uphill to join the other path instead. These two forking paths come together after a while anyway, fortunately for me, just before a crossroads of sunken tracks worn into the hillside - these are old drovers' ways i.e. paths shepherds used for centuries to move their sheep from place to place.
The start of the bridleway from Whipsnade to Bison Hill
The bridleway to Bison Hill
View from Bison Hill
Path on top of Bison Hill (by the car park), just before I forked left
Path on Bison Hill - I forked left just before the trees, only to find the path blocked by thorny bushes, so I then joined the path that forked right
Path on Bison Hill (after taking the left fork)
The path that was the right fork, just before it reaches the crossroads of sunken tracks
I went straight on here, dropping more steeply downhill. At the bottom of the slope I followed the path as it curved right and passed just left of a large pylon. Soon the path was again a sunken track with an embankment on my left, gradually working its way back up the hillside.
The old Drovers' Way descending Bison Hill (after the forking paths had rejoined
The old Drovers' Way descending Bison Hill
The old Drovers' Way descending Bison Hill
The old Drovers' Way slowly ascending Whipsnade Downs
The old Drovers' Way slowly ascending Whipsnade Downs
View along the Whipsnade Downs and Dunstable Downs, from near the end of the old Drovers' Way