Historical context

Before the 18th century and Pasteur’s discovery of the germ, illness was seen as an imbalance of the body, mind and environment of the patient. In this time, diagnosis was purely speculative through discussion between the patient and the practitioner, and postmortem autopsies were not often practiced, at least to the public eye. 

In the early decades of the 19th century, medicine took a shift away from patient imbalance, and became focal to organ and tissue lesions. This was to a large extent due to the practice by Parisian hospital schools where postmortem analysis grew to become a common mode of education for their students. Medical training took a change to include dissections for hands on experience of the body, and disease causation became the centre of interest rather than patient therapy. 

An Illustration of experiments with executed corpses
http://www.executedtoday.com/tag/murder-act-1751/

The Murder Act of 1752, allowed bodies of executed criminals to be dissected, which became the main source of cadavers. [1] But as anatomy became more essential to medicine for educational purposes as they provided a great visual aid for training, demand for cadavers increased and exceeded their given source. Soon enough, institutions began finding illegal ways to claim bodies for dissections and research, such as taking unclaimed bodies of paupers, and resurrectionists who were paid to obtain bodies by robbing graves. Cases of murders, such as those by the infamous Burke and Hare, were carried out to sell their corpses in exchange for monetary value. However, these ways soon became stigmatised by the public, leading to the passing of the Anatomy Act 1832, which legally licensed doctors and medicine practitioners to dissect bodies that were unclaimed and prevented the need for such crimes.

Although the Act was successful in putting an end to resurrectionists, there is no avoiding that the incident induced public fear and may have kick-started the rise of public mistrust in medical systems prior to the Alder Hey scandal. The scandal was justified in the eyes of medical professionals as bodies and organ retention was done with good intention. Van Velzen, the main pathologist accused responsible for the scandal, claims it was in the best intention of the family of the child, to investigate the cause of death, and was done so with parental consent whether or not they were aware that it entailed removal of all organs. [2]  

The fear induced by this scandal set the creation of the Human Tissue Act 2004, to which informed consent for any removal, storage and use of human organs became necessary under the law. [3] The Act also assured the public that all activities involving cadavers were carried out with respect to the cadaver and their families. The historical lead up to what post mortems are today was essential in having the knowledge and respect for bodies, but is deeply traumatic and has skewed public conceptions of medical systems. 

1. P. Mitchell, et al. “The Study of Anatomy in England from 1700 to the Early 20th Century.” Journal of Anatomy 219(2) (2011): 91–99
2. "Van Velzen interview in full" BBC News. February 5, 2001. http://news.bbc.co.uk/2/hi/health/1154181.stm
3. "Human Tissue Act 2004" Legislation.gov.uk. http://news.bbc.co.uk/2/hi/health/1154181.stm