Bean, C. E. Archaeological Discoveries in Sherborne and District vol. 72, p.76
After asking the former vicar, I discovered that these burials had been shallow and hasty. His theory was that a skirmish had broken out between cavaliers and roundheads, and they were buried where they fell. Where Sir Arthur Keith - who was notably mixed up in the Pitdown Man hoax - got the Norman idea, I haven't a clue.
I was worried that either the 'burials' were surmised (empty graves), that the little skeletal material recovered was languishing in an unmarked box in a museum somewhere, or worse, had been lost entirely, but I needn't have panicked. After they were excavated they were respectfully re-interred in the new cemetery extension.