Place all the ingredients in a large saucepan and heat gently, stirring until sugar dissolves. Bring to a boil. Cover and boil for three minutes. Uncover and continue to boil until the temperature reaches 116C/240F. Remove from heat and beat until the mixture becomes thick and creamy. Pour into a greased 8-inch square pan. After thirty minutes, mark into squares with a knife then let set. Cut into pieces and store in an airtight container.