As perceived merit decreed, a prisoner could move on to the third stage – the attainment of a probation pass with which he might gain paid work. There were three classes of pass that differed primarily in the proportion of wages that the convict received with the rest being held in account by the Government. The probation pass could be revoked for misconduct, and the convict returned to the probation gangs. Gaining a ticket-of-leave was the fourth stage, which was valid only within the colony. The final stage was the pardon (either conditional or absolute).
The system had various shortcomings, and several modifications were made to the system by Secretary of State for the Colonies, Lord Stanley, and his successors, Gladstone and Earl Grey.
REFERENCE: FLINDERS UNIVERSITY MARITIME ARCHAEOLOGY MONOGRAPHS SERIES Number 7