Scrub the fruit and cut up roughly, discarding the pips, then mince into a large bowl.
Add the water and leave to soak overnight.Put the contents of the bowl into a preserving pan or large saucepan and bring to the boil: simmer for one hour. (The contents of the saucepan should weigh no more than 2 kg a this stage).
Add the Sure-Set and stir until dissolved; then bring back to the boil and boil vigorously for 4 minutes. (See 'Adding Sure-Set' for details on boiling and timing).
Allow to stand for about 5 minutes, stirring occasionally to distribute the peel.
Then Pot and cover in the usual way; label and date. (See 'Potting and covering' for details).