|During the late 50's it was determined that:
a)HMAS Melbourne was too small to operate modern aircraft,
b)There was no suitable (read affordable) light carrier designs available as a new build replacement,and
c)Existing surplus ships available for purchase from our allies were seen to be too large and needed too much man power.
As a result of this it was decided to convert HMAS Melbourne into an ASW Helicopter Carrier while HMAS Sydney would serve as a Training Ship and Troop Transport.
Due to the deteriorating security situation in the early 60's this decission was reversed with the Sea Venoms and Gannets being retained in service until the late 60's when they were replaced with Skyhawks and Trackers.
My hypothetical is that the original decission was not reversed and the conversion went ahead with the increasing threat of Nationalist Indonesia and the Communist expansion into Asia being addressed in other ways.
-HMAS Sydney was also converted into an ASW Carrier
-The requirement for DDG's was changed to DLG's to improve fleet air defence
-We kept a watch on developments in V/STOL as an affordable path to reform the FAA's strike and air defence capability in the future if required
-We also kept an eye on the RN's Escort Cruiser Program as a possible replacement for the ASW Carried in the 70's/80's.
-All future major surface combatants would be multi role destroyers with Area Defence Missiles
-We bought into the UK/Dutch SeaDart program as Terrier was seen as too large for Destroyers, Tartar was seen as lacking in performance and Typhon was seen as too expensive and risky.
-All future small escorts were down graded to Corvettes
-The Submarine Service was brought forward and expanded with SSN option being investigated for the future
-Existing fixed wing RAN FAA squadrons were transfered to the RAAF
-The RAAF used the FAA sqns to double their MPA sqns from 2 to 4, and to split their fighter force into 3 Interceptor, 3 Tactical Fighter / Attack and 3 Strike recon. More capable aircraft were aquired to help in the Fleet defence and maritime strike role they had assumed.