Halve the fruit and squeeze out the juice into a pan, reserving the pips. Remove the pith from enough rind to give 60g (2oz) rind from each 500g (1lb) fruit. Shred this finely and place on a square of muslin with the pips and tie loosely. Add to the pan. Cut up the remaining pith and rind and add to the pan with the lemon juice and water.
Bring to boil and simmer for about 2 hours: remove the muslin bag after 1 and 1/2 hours to prevent the rind becoming to soft; keep this on the side.
Strain through a jelly bag and test the juice for pectin: it should form a firm clot. Put into a pan and add the sugar.
(warm the sugar first) and the strips of rind, (not pips) from the muslin bag.
Heat gently, stirring until the sugar dissolves, then bring to boil and boil rapidly until setting point is reached.
Remove from the heat, skin off any scum, and leave to stand for a few minutes. Stir again and pour into hot sterilized jars. Put in the waxed discs and cover when cold.