Well, another mathematical FTF! There were plenty of objects here (unspherical though they were) with which to try a physical demonstration of our cannonball solution, but we were on a Caerphilly Crusade today and didn't want to lose the time.
Two young and friendly horses came around the fence to sniff at what we were up to. We tried to pet them, but they couldn't overcome their wariness.
We thought the difficulty of this cache lay not in the maths but in the maps: half the paths the map shows don't seem to exist; and half the paths that do exist aren't on the map! We guess that leaves the map good for about one-quarter of local reality.
Thanks for bringing us to this quiet spot. (Quiet, that is, until we descended the hill -- serenaded the entire way by an endless loop of the Teddy Bears' Picnic!)