Combine all ingredients in a medium saucepan. Cook and stir over medium high heat until boiling. Clip candy thermometer to side of pan, cook and stir over medium heat, til syrup reaches temperature 238F (155C) on candy thermometer (soft ball stage) 25 to 35 minutes. Remove from heat and cool without stirring to lukewarm (110F/45C) about 50 to 60 minutes.
Remove candy thermometer and beat mixture with wooden spoon until colour lightens and fudge begins to quickly set. Quickly press into well greased 8 inch square pan. Make in squares before fudge sets. When firm, cut into squares. Makes 20 to 25 pieces.