Rub off any fuzz and wash thoroughly. Remove stems, blossom ends and damaged parts, then chop into roughly 1–2 cm pieces, retaining the skins and cores.

Put the quinces and water in a large saucepan. Cover, bring to the boil, then reduce to a gentle simmer. Cook for approximately 45 minutes, stirring occasionally, until the pieces crush easily with a spoon.

Pour the fruit and cooking liquid into a damp jelly bag or muslin-lined colander over a deep bowl. Let it drain naturally until the dripping has slowed substantially. Do not press or squeeze.

Expect approximately 1 litre juice, although the yield will vary. For this quantity, add 710 g sugar and 75 ml lemon juice. For other yields, use approximately 675 g sugar and 70 ml lemon juice per litre of juice.

Transfer the juice, sugar and lemon juice to a wide, deep saucepan with plenty of room for bubbling. Heat gently, stirring until the sugar has completely dissolved. Put two small plates in the freezer.

Bring to a full rolling boil. Begin checking after 5 minutes; approximately 10 minutes may be sufficient, but use the setting test rather than time alone.

Remove the pan from the heat. Spoon a little jelly onto a chilled plate and cool for 1–2 minutes, then push it gently. It should wrinkle slightly or form a soft mound that holds together rather than flowing back immediately. If still runny, boil for another minute and retest.