People   (Re-unions, trace old friends and relatives.)

I think the fact that the deaths are generally of males, who would have been in their prime rules out illness. Also there would be large amounts of burials over a longer period and not just one day. Also the surrounding parishes show nothing unusual at the time. The logical reason would be a pit explosion or work disaster of some kind, but as Gaffer points out there is seemingly no record of one. It's sad but interesting, and more digging is needed. Definitely no pun intended.