Duffy asks whether a fourth and possibly a fifth Invincible should be ordered if the class is to be cost-effective. Three ships could not reliably cover their assigned role while also meeting detached deployments, a promised global role, and periodic refits. The impending withdrawal of Bulwark and Hermes would remove other flight decks that might absorb those tasks. His concern is therefore simultaneous availability rather than the headline size of an individual carrier. The later readiness calculation starts from this fleet-count problem.
Notable Point · 36:01-36:31
Three Invincibles cannot cover deployments, global roles, and refits
Duffy argues for a fourth and possibly fifth carrier because three hulls cannot sustain detached operations and refits after Bulwark and Hermes retire.