This is some very niche Melbourne based history.
It was on 29 June 1959, that our founding fathers met in Reg Buchanan's home in Balwyn, Victoria, where they made the historic decision to form a hardware/building supplier group. Legend has it, that the Mitre 10 name was born out of a subsequent visit to the reknown drinking premise, the Mitre Tavern, but our founding fathers would say it comes from the carpentry term to join two pieces of timber together at a 90 degree angle. By forming Mitre 10, the foundation members etched their names in history as a part of a hardware industry transition from the independent to the group retailer.
The Mitre Tavern is also apparently the oldest building in Melbourne according to this video. Might need to go have a pint of Guinness from there sometime.