Louis Hughes' son, John, 39, a taxi driver, said: 'What happened was diabolical. My father was left lying in a stinking toilet for 36 hours.'
His father, who had a history of heart trouble, had been treated several times at the hospital and agreed to be examined at a students' seminar. But when members of the family went to the hospital the following morning they were told 'categorically' that Mr Hughes was not there.
'That is just ridiculous,' John Hughes said. 'They had checked and knew he had been at the students' seminar. Once they knew he was missing, the ward and the toilet should have been the first place to look. We are considering whether to take some sort of action. We just want to get the funeral out of the way.
'Personally, if someone from the hospital was to come and apologise and explain how it happened that would help. I want an assurance that it won't happen to some other poor person in the future.'
The hospital said later it would tighten procedures following Mr Hughes' death. Professor Tony Freemont, hospital dean responsible for education and medical students, said staff were 'absolutely shocked'.
A spokeswoman said Mr Hughes was apparently not found immediately because his relatives had not gone to the part of the hospital where he helped in the students' seminar, but to where where he was treated previously. Several medical examinations were taking place in different parts of the hospital on the day in question, and by the following morning representatives of the medical school were not in the hospital to be questioned about Mr Hughes.
'A proper search was instigated on the Saturday morning,' the spokeswoman said. 'It is an enormous site with three huge hospitals on it. The place where Mr Hughes was found was not the obvious area to search first, because it was not used at weekends and the people searching were not aware that was where he had been.'