What would let Australia and New Zealand survive Washington?

What would have to be different about HMAS Australia and HMS New Zealand to justify Britain fighting for their retention at Washington?

Their orders would need to be delayed until they could be built as 15-inch-gun Tiger derivatives, their wartime service would need to demonstrate their value, and Washington would need a separate battlecruiser category with Dominion entitlements.

The patron's question asks what would have to change about HMAS Australia and HMS New Zealand for Britain to fight for their retention at Washington. The proposed answer begins with delaying their orders until an enlarged Tiger design with 15-inch guns becomes a plausible choice. Better wartime performance and a demonstrated need for commerce protection would give those ships a stronger retention case than the historical Indefatigables. A separate battlecruiser category, with Dominion entitlements, would then provide a treaty framework for keeping them. Each stage is part of an alternate history, and the diplomatic compromise remains conditional.