Could any country besides Britain have developed 14-inch naval guns sooner?
Short answerThe United States is the likeliest rival; other firms had capabilities, but their funding, industrial scale, or political priorities made the programme less viable.
NotesThe United States is the likeliest alternative because Britain and America have industrial organisations large enough to fund and pursue the programme. Germany's Krupp could in theory contribute, but shifting development effort from land weapons would create a difficult argument with the Army. Austria-Hungary's Škoda has the technical capacity, yet lacks the comparable funding and intent. The distinction is between being able to build a gun and having an institution willing to pay for its development.