For example, consultants to the Department of Health proposed that a single TTP be established to certify all keys used in the practice of medicine. The medical profession found this unacceptable, as this would entail the TTP taking over the function of medical registration, which has for generations been carried out by the GMC. The Department's consultants suggested that this body should control the TTP; but this was not acceptable to nurses, who have a different registration body (the UKCC). It was then suggested that the nurses, and other healthcare professions, would have their own TTPs too. However this would mean that in order to send a message between a doctor and a nurse working in the same practice, both TTPs would have to be involved in the supply of keying material.
Even a proposal (in New Zealand) that medical keying material be generated in hospitals and sent out to the medical practices that feed it with patients, turned out to be unworkable, as only the staff in a medical practice know who is employed there and are in a position to manage access control to local systems effectively. If central control were to be enforced, then whenever a locum or agency nurse were hired for the afternoon to cover for absent staff, an interaction with a TTP would have to take place.