Why Royal Oak's exact wartime complement is difficult to pin down

How many people were aboard Royal Oak when she was sunk?

The exact total is disputed because nominal complement, wartime assignments, and actual presence aboard do not necessarily match.

A ship's nominal complement differs from the number assigned in wartime and the number physically aboard on the night of loss. References to a higher wartime total do not necessarily prove everyone recorded against the ship had embarked. The surviving figures do not all reconcile, and the caveat is explicit: this aspect had not been researched in depth. Casualty totals, complement tables, and actual presence can therefore answer different questions.