Thanks for that, must have missed your original postAgain I don't know if I'm right or wrong, but it does appear likely when comparing the two photos.
With JC1 being first of class there was bound to be changes made for follow on ships, apart from specific Australian modifications to the original design.
If it is what I think it is, maybe there was an issue with the arm being mounted down too low on JC1, maybe the mount on JC1 might change in the future too.
The protrusion on Canberra looks bloody ugly, but obviously its been positioned there for a reason.
Looking at the 2 pictures what you say makes sence, because the Canberra does not have the RAS station on the STBD side of the island as the JC1 does that gives it the capability to refuel escorts, there would possibly be a change and requirement for different rigging on the front of the bridge for our requirements
Cheers