I believe the safari roof was standard on all Series station wagons (I have never seen one without), so not specific to the navy.
The number plate is a Queensland one of the type introduced about 1955 and replaced only a few years ago.
According to Taylor, total Normal Control Series 2a production was 343,298, not including military lightweight vehicles. Of these about 48,000 were 109 station wagons. So I do not know where the figure of 3,000 came from - the smallest number variant I can find is 811 for the North American six cylinder station wagon, and 4,949 for the six cylinder station wagon excluding NA.
One possibility is that the number of could be that low if you only included a particular variant with the headlights in the mudguards (change about 1969).
John

