Calling the Type 45 a one-billion-pound destroyer confuses total programme spending with the cost of building another hull. The six-ship programme averaged about £1 billion per vessel because that figure absorbed research and development. The figures in this passage put construction below £500 million, later units below £400 million, and possible follow-on ships around £300 million. On that illustrative arithmetic, extending the class toward twelve ships would have bought much more fleet availability for less than twice the programme total. Plan Z faced the same problem in another form: repeated German design changes incurred new development costs, lengthened construction, and added refit and training burdens instead of exploiting a mature class.
Notable Point · 28:44-30:16
Why Type 45 programme cost was not the cost of another ship
Separating already-paid design costs from the falling price of follow-on Type 45 hulls shows why small classes waste development work and why Plan Z's constant redesign was expensive.