Why modernize Courageous or Glorious instead of building a Malta-class carrier?
Short answerMalta would be better, but an upgrade used much less scarce yard capacity and returned a carrier to service far sooner.
NotesA new Malta would offer much greater capability than a rebuilt Courageous-class carrier. The wartime constraint is the large slip and roughly two-year construction commitment required for a new fleet carrier. A shorter modernization and fitting-out period could be accommodated by more yards. An old carrier might also be sent to the United States or another overseas yard, spreading the industrial burden.