Implacable and Indefatigable belonged to a separate class from the four Illustrious-class carriers. The two groups shared design-study ancestry, but they were different designs. Implacable and Indefatigable were intended for a strike-carrier role from the beginning. The earlier armoured-hangar carriers had a stronger fleet-carrier emphasis.
Notable Point · 37:01-37:33
Illustrious and Implacable had different carrier roles
Shared design ancestry did not make Implacable and Indefatigable members of the Illustrious class; their intended emphasis on carrier strikes distinguished them.