CREATE TABLE table_21903 ("Year ( s ) " FLOAT, "Final television commentator" TEXT, "Radio commentator" TEXT, "Spokesperson" TEXT, "Semi-final television commentator" TEXT, "Semi-final second television commentator" TEXT)

Who was the radio commentator when the final television commentator was John Dunn?
SELECT "Radio commentator" FROM table_21903 WHERE "Final television commentator" = 'John Dunn'
SELECT "Radio commentator" FROM "table_21903" WHERE "Final television commentator" = 'John Dunn'