Grant or Staghound Turret Ring?

[David Herbert]

The grant ring has the top surface where the heads of the bolts to the hull are on a slope of about 15 degrees. Your photo apears to show it flat so I don't think it's Grant. Matilda is very similar to Grant which leaves Staghound as a posibility. There are of course lots of other turreted vehicles that were used by Australia. Counting bolt holes might narrow it down as would measuring its diameter but published figures don't always measure the same thing - Inside dia., Outside dia., Pitch diameter of ball path etc.

David