Peel pumpkin and cut into 2.5cm (1 in) cubes. Place into a big saucepan with water and boil for 5 minutes. Strain well and set aside.
In another saucepan combine pickling vinegar, malt vinegar, sugar and ginger. Boil for 5 minutes. Add cooked pumpkin cubes to vinegar mixture. Boil together for 45 to 60 minutes till most of the liquid has evaporated. Pack in screw top jars.