Note 275 — NOTE W.
Reading edition
And it is possible that, as Koppel suggests, the Doctor should properly enter at this point; for if Kent, as he says, wishes to remain unknown, it seems strange that he and Cordelia should talk as they do before a third person. This change however is not necessary, for the Doctor might naturally stand out of hearing till he was addressed; and it is better not to go against the stage-direction without necessity.