Hi Westy
Common burial is the term for a grave in which no private burial rights existed. Families could just about afford a very basic burial but not a private grave so common graves could be filled over the course of a few days with the bodies of unrelated people who died during that time period.
Have come across family together if they died within a period close together.
Unconsecrated ground as I understand were for non-conformist religions, those buried in consecrated ground would have been members of the Church of England. I know there are other things to consider such as suicide which might affect a burial but thought this was a good explanation
http://www.rootschat.com/links/01mok/When most cemeteries were designed and opened, certain parts were formally blessed by dignitaries of the Church of England, thereby consecrating the ground prior to burial. However, it was also recognised that people from other religious denominations such as would also wish to be buried in the cemeteries, therefore some areas were left unconsecrated by the Church of England.
When a burial takes place in an unconsecrated part of the cemetery, the minister representing the religious belief of the deceased will conduct a service at the graveside, thereby blessing that individual grave at the time of burial.