Cowardice is a vice. Conventionally it is the corruption of prudence. Cowardice may be considered to be prudence that does not take consequences to their furthest extent.
Cowardice is not fear, but rather a submission to vice that uses fear as a pretext. Here's an example of virtuous fear: We all fear to dive head-first into a swimming pool the depth of which we do not know. An example of cowardice would be to refuse to testify against a crime lord, merely because one might risk death.
As he points out, though Coward's writing grew more polished as the years went along, and though he attempted to change with the times, essentially for almost 50 years he wrote biting satire built on mannered epigrams and gestures and brilliant effects and ripostes.
Coward was attracted to and proficient at music and the theater from an early age.
While Coward deplored the stigma attached to homosexuality, he chose not to make a public issue of it (not that anyone could during most of his lifetime).