With the car off the drive, and selecting waypoints away from significant obstacles, I got this:
Still not perfect – there’s 2.5m meters between the identical start and end points, but it’s good enough. Waypoint 3 here is probably to blame; I think its distance from waypoint 2 is too far – it’s certainly the most ‘clustered’ point in the test with a tree, a stone wall and overhead telephone wires all within a few meters of it. The first two waypoints will suffice by starting the flight half way between two and three, so the flight goes south for 4.5m before flying ENE by another 4 meters. All 3 points (takeoff and the 2 waypoints) have no obstacles, so Sweep can be enabled to land the test flight if a code or GPS waypoint error brings Hermione to within a couple of meters of an obstacle. That’s what I’ll be trying next.