Carrier aviation in a stronger post-imperial Commonwealth

Would a non-declining Britain or Commonwealth still need Harrier-like aircraft?

Yes; shared large carriers would not remove the need for smaller members and secondary missions to use fast aircraft with short- or vertical-launch flexibility.

The premise is narrowed from an unchanged empire to a world without a second global war, allowing Britain to complete a transition toward a first-among-equals Commonwealth. Its strength would come from economic weight, technology sharing, officer exchanges, and a mutual-defense expectation across otherwise separate states. India could become a powerful member if decolonization left it enough autonomy, while African participation would depend heavily on how that transition unfolded. Britain, India, Canada, and Australia might jointly design large carriers, share training and maintenance, and distribute conventional or nuclear variants according to national needs. Smaller members could still want ski-jump ships or LHDs, while a continuing requirement for aircraft that combine speed with vertical access supports a Harrier-like capability.