What national capability contributes to an alliance

In the Dominion battleship counterfactual, Australian capital ships and the yards needed to support them would give Australia more capacity to respond before outside help arrived. A state able to defend itself and contribute useful forces gives its partners a stronger reason to assist it. The comparison then turns to Britain supplying a carrier, auxiliaries, and core escorts around which an allied task group can form. That contribution becomes harder for partners to accommodate when Britain depends on their escorts for deployment. They must then divert ships from their own requirements instead of contributing only when they have spare capacity.