Quotes from the news wire:
This mass burial, so different to the other individual burials found in the Bedlam cemetery, is very likely a reaction to a catastrophic event, only closer analysis will tell if this is a plague pit from the Great Plague in 1665, but we hope this gruesome but exciting find will tell us more about one of London's most notorious killers.
The particular question is, what was responsible? Actually what pathogen, what bacteria formed the Great Plague outbreak in the 17th century? it doesn't seem to come back, so something changed in the way people were living. People say the Great Fire of London in 1666 had something to do with the ending of Great Plague events, but through the scientific studies we can do these days on DNA from samples of these skeletons, we might be able to tell what pathogen is responsible for that outbreak and perhaps why it stopped.
1665 was the very last recorded episode of plague. There were 400 years of regular plague, and suddenly it stops, and what we want to be able to find out, from sampling the graves of that date, is why that is. And what it is about the bacteria that causes bubonic plague that suddenly changed at that point.