Estimating the Cornish share of destroyer captains

How many British destroyer captains came from Cornwall?

The rough estimate is about four to five percent, with uncertainty over who counts as Cornish and a clarification that the comparison concerns sailors and maritime people.

Counting Cornish destroyer captains is complicated by the difference between coming from Cornwall and later living there. The rough estimate places their share slightly above the relevant population share, at about four to five percent of destroyer captains. An initial reference to population is then qualified as sailors and maritime people. The figures are offered as estimates, with that denominator correction essential to their meaning.