Rub the grey fuzz off the quinces with a cloth, then wash them. Cut into small chunks, keeping the skin, core and seeds; they hold a lot of the pectin.

Put the quince pieces in a large pot with the water. Bring to a boil, cover and simmer for about 25 minutes, until very soft.

Pour into a damp jelly bag or a colander lined with several layers of damp cheesecloth over a bowl. Let it drip for several hours or overnight without squeezing.

Measure 3 3/4 cups of juice. Prepare a boiling water canner and sterilise the jars by boiling them for 10 minutes. Chill a few small plates in the freezer.

Put the juice and lemon juice in a wide pot, bring to a boil and stir in the sugar until dissolved.

Boil hard, skimming off foam, until the jelly reaches 220°F (104°C), or 8°F above the boiling point of water where you live. Check with the cold plate test: it should wrinkle when pushed.

Ladle into the hot jars, leaving 1/4 inch headspace. Wipe the rims, add lids, and process in a boiling water bath for 5 minutes (adjust for altitude).

Cool undisturbed for 24 hours and check the seals.