In Clarke's account of the programme, design work precedes the main submarine procurement phase. He describes a 2028 order as the existing plan tied to the Dreadnought programme. Some long-lead items would be purchased earlier. Their details are still presented as needing final agreement with Australia, which is said to be due the first submarines.
Notable Point · 33:02-33:44
Design work and long-lead items before an AUKUS order
The claimed 2028 submarine-order timetable allows for design work and purchases before the main contract.