The Arethusa class was a smaller Leander with three twin 6-inch turrets and unit machinery intended to preserve power after adjacent compartments flooded. Both the Home and Mediterranean Fleet commanders disliked providing cruiser aircraft, because they expected carrier reconnaissance, while the Admiralty Board and Controller required reconnaissance capability for possible trade-protection duties. Applying unit machinery to the modified Leanders lengthened the protected machinery spaces, reduced accommodation, increased beam and complicated the catapult position. A proposed increase to nine or ten guns depended on a new triple turret that might not be ready, so only the machinery change proceeded. Phaeton became HMAS Sydney, while Amphion and Apollo later entered Australian service as Perth and Hobart. Survivability requirements and aircraft provision consequently shaped both displacement and Commonwealth procurement.
Chapter · 2:21:55-2:25:29
Arethusa and Leander trade-offs reached the Australian Navy
The later portion of the Warships after London review follows cruiser machinery, aircraft requirements, protection, and the transfer of modified Leanders to Australia.