The cardiologist had his contract terminated in January after allegations he had to be stopped by a patient's wife from using a medical spray that he had removed from his own pocket and claimed to have already used on himself and on another patient.
The woman stopped consultant Geoffrey Fielden Baines administering the spray to her husband and gave the consultant the patient's own spray. He had earlier misdiagnosed the patient, saying he only had indigestion and not a heart complaint.
The family's intervention resulted in another doctor attending to him at Western Isles Hospital in Stornoway and their formal complaint about Dr Baines was upheld by the health board.
It has also emerged that another locum consultant in geriatrics, who was 77 years old, had his contract terminated at the same hospital in 2008 after a complaint that he put a "Do Not Resuscitate" notice on a patient without telling the relatives or filling in the necessary paperwork.
Dr Peter Paul Meisner had misdiagnosed the man's condition over a period of months. When he was eventually properly treated, the patient died within five days.
The dead man's family made a formal complaint and was told there were other complaints against him and he no longer worked for NHS Western Isles.
Despite the apparent serious nature of these incidents, neither consultant has been banned by the General Medical Council although a formal warning notice has been circulated about Dr Meisner's improper conduct towards a consultant colleague and a hospital receptionist.
Dr Baines is still fully registered with a licence to practice.
Dr Jean Turner, the executive director of the Scottish Patients' Association, said: "The best scrutiny should apply whatever the age or the area of expertise of the health professional or the geography of the area in which the health professional is to work."
Staff consultants must all retire when they reach 70. However, a loophole in NHS contracting policy allows doctors over 70 to work as locums after they reach that age provided it is for no longer than two months in every nine.
Dr Baines gained his MB ChB at St Andrews and gained his full registration on August 2, 1957. Dr Meisner gained his medical degree in 1960 at Durham University. He became a specialist in Geriatrics in 1999 when he was about 69.
NHS Western Isles insisted that its recruitment of all staff follows a robust process, including checking references, standard disclosure checks, checking GMC licences and obtaining Fitness to Practice statements.
Its statement added: "Both gentlemen referred to were recruited through accredited, approved agencies, and all necessary checks were carried out prior to starting work." The Scottish Government said it was committed to ensuring that all communities, including those in remote and rural areas, received safe, reliable and sustainable health care services.
A health department spokeswoman said: "It is the responsibility of individual health boards to ensure they provide primary medical services to meet the reasonable needs of their population, and it is for each board to determine how they provide that service, including the use of locum doctors."
The Scottish Government said it expects all boards to apply the same stringent measures when it comes to the recruitment of doctors in their areas.
Neither of the consultants could be contacted for comment.