Four junior members of the Lodge of Progress 5017, having heard the then Provincial Grand Master, RW Bro The Rev Dr Joseph Moffett, observe on an installation visit to Lodge of Progress, that with a membership of over one hundred, they should have another birth. There was already a daughter Lodge, Prospect No. 6748, but contemplating that the then average time to the master's chair was in excess of fifteen years, it was decided to form a new Lodge.

The name had to begin with the letters PRO and after much research, a combination of Latin and Greek was selected: Probatus, meaning tried, tested and approved. The badge depicts the world chained and encircled by a ring representing the strength of freemasonry universal, also shown are the dove of peace, the sword for justice, and the VSL for truth. The lodge was duly consecrated on 14th November, 1966. It does not possess a banner.