I found a photo of FGM's property which shows a retaining wall beside the lower driveway (the driveway which leads into the downstairs garage). Here's a magnified section:
View attachment 244206
It's easier to see context in
the full photo in the archive, but the section of the house shown above in the middle of the shot is the side which overlooks the driveways.
Does anybody know if there's a wall on the other side of the house too - between the upper lawn (where FFC last saw William) and the lower lawn (at the southeast corner of the house near the under-verandah water tank)? I have not been able to find any good views of that side of the house: it's always in shade, behind trees, or too far away to see details. If there
is a wall it might have obstructed movement or forced a detour for William or an abductor.