Again, this probably should be on the forum but for those interested in the purported 1258 volcano that caused a famine that killed lots of people in cities such as London it is bit revealing that earlier this year Michael Mann, infamous for creating a hockey stick by hiding the decline and making use of bristlecone pines that were influenced by snowfall in the high mountains rather than global temperature, had a piece published in Nature Geoscience that perhaps kickstarted all the other articles and possibly even the reason why archaeologists thought a volcano was responsible for the mass burials at a cemetery in Spitalfields, rather than an epidemic. I can't actually make out if a volcano did occur in 1258 and having looked at a bit of local history in that period nothing much out of the ordinary appears to have happened. The Mann article can be accessed at http://xa.yimg.com/kq/groups/18383638/1363288851/name/ngeo1394.pdf
However, as in everything to do with Michael Mann there is a story inside the story – and I still don't know if a volcano blew in 1258 – go to http://climateaudit.org/2012/10/20/a-belated-si-for-darrigo-et-al-2006/