Yes, it is a fine picture of a notable old veteran (the tank, not the driver, ..... well, maybe the driver too....!)
Interesting you should define MBT as Medium Battle Tank (rather than the more usual Main Battle Tank): The 'Medium BT' was a term that was used in some (few) official Aust publications, and in reference to Leopard AS1 no less(!), so as 13B says, no hard and fast rules with this one.
As I said, I do not take exception to the description Centurion MBT one little bit, but there are those that have. I was involved in an exchange on the subject on another forum: its just a pity the respondent was not better informed about both the Australian official nomenclature for the Centurion, nor the extent of the official use of the abbreviation 'MBT' with regard to Centurion during the last several years of its service. You can take a horse to water but.....
Mike C