The informant usually has to be one of:
someone present at the death
someone in attendance
the occupier of a house
the master or keeper of an institution
a person who found the body
inmate of a house or institution - this was a person living at the same address who knew of the event
person causing the burial
person in charge of the body
Normally it is a relative, or someone at the hospital or nursing home where the decesed died.
In this case there was unlikely to be a relative?