Place all the ingredients in a large saucepan and heat gently, stirring until the sugar dissolves.
Bring to the boil, then cover and boil for a further 3 minutes. Uncover once more then continue to boil until the temperature reaches 116 °C (240 F).
Remove from the heat and beat until the mixture becomes thick and creamy. Pour into a greased 20 cm (8 inch) square tin. Leave for 30 minutes.
Mark into squares with a knife and leave until set. Cut into pieces and store in an airtight container…or eat immediately!