In Victorian and early Edwardian times the infant mortality rate was high and in fact life expectancy in general was far less than it is today. Parents may not have had their child photographed when they were alive and in the event of a sudden death take a post-mortem photograph of them.
Some of these photographs were tastefully done showing the obviously deceased child laying on a bed surrounded by flowers and apparently asleep. However, if the family did not have a photograph of their child or family member when they were alive they would instruct the photographer to give the impression that the deceased was still alive at the time of the photograph.
It was extremely expensive to have a photo taken during Victorian times. Only the wealthy could afford such a luxury. If a child or other loved one died it was a common practice to have a photo taken either alone or with the family.