Why could HMS Emperor of India and HMS Empress of India not be used as ship names at the same time?
Short answerThey were too similar operationally, and only the reigning sovereign held the emperor or empress title while the spouse was the consort.
NotesHMS Emperor of India and HMS Empress of India should not be used at the same time for two reasons. The names are similar enough to invite confusion in orders and communications. They also imply two simultaneous holders of an imperial title when the reigning sovereign would be either emperor or empress and the spouse a consort. Naval naming therefore had to account for both operational distinctiveness and constitutional usage.