The five flight decks counted are HMS Ocean, RFA Argus, and the carriers Invincible, Illustrious and Ark Royal. Reducing that count to Queen Elizabeth and Prince of Wales is used to explain limits on carrier availability. Argus was still active at the time of the discussion, with other duties that limited her role in this comparison. The discussion separates the decision to replace five decks with two from the 2010 decision blamed for the aviation gap.
Chapter · 10:13-10:50
Replacing five British flight decks with two carriers
The count of British flight decks falls from five to two in an argument about availability, with Argus's continuing but different duties explicitly acknowledged.