Wartime pennant letters did not always provide the simple type labels suggested by the film example. Destroyers could appear with different letters as the Royal Navy altered its markings. The explanation given is an effort to make ship identification harder for the enemy. The resulting confusion eventually affected the Navy itself and encouraged standardization.
Notable Point · 5:18:17-5:18:40
Why wartime pennant letters could confuse ship identification
Changing pennant letters complicated identification until the system also became confusing for its own users.