Wey, you could be right Megadread, they are pretty unusual motifs.

But.

According to my hasty googling, the Rev E died in 1717 and the first open air RA in Britain wasn't recognised as ancient until1826 (ish), so if the good reverend had made the carvings at Rowtor, or had them comissioned, it would only deepen their mysterious nature, as how the heck would he have known over 100 years before anyone knew the things he was copying existed? That would be proper weird :)