Can you Identify this Knight?

Could any members help in identifying the subject of this portrait? If you can, please contact Richard d’Apice direct, who has written as follows:

I seek your assistance  in my attempts to obtain information about the subject of the attached portrait which I recently purchased in Sydney. On purchase the subject was unidentified but, in a previous sale, I find him identified as Joseph Gates OBE. The OBE must have come after 1972 as he is not wearing it in the portrait which carries that date.

The artist is Anthony Harper whom I have difficulty in identifying.

Richard d’Apice AM KCSG KGCHS,
Secretary and Treasurer, Association of Papal Orders, Australia