Prepare the fruit – Wash the oranges and lemons thoroughly. Cut them in half and squeeze out the juice, collecting it in a large bowl. Remove the pips and set them aside, as they contain natural pectin.

Slice the peel finely – Scoop out the flesh and pith from the orange halves, then slice the peel into thin shreds. Even slicing helps the peel cook evenly and look neat in the finished marmalade.

Tie the pips – Place all the reserved pips and pith into a piece of muslin and tie securely. This allows the pectin to release during cooking without clouding the marmalade.

Cook the fruit gently – Put the sliced peel, juices, water, and the muslin bag into the preserving pan. Bring to a gentle boil, then simmer until the peel is completely soft. This stage can take up to two hours and is key to a good texture.

Warm the sugar – While the peel cooks, warm the sugar gently in the oven. This helps it dissolve quickly and prevents the marmalade temperature from dropping later.

Add sugar carefully – Remove the muslin bag, squeezing it well to extract as much pectin-rich liquid as possible. Add the warmed sugar to the pan and stir over low heat until fully dissolved.

Boil to setting point – Increase the heat and bring the marmalade to a rolling boil. Boil rapidly until setting point is reached, testing regularly using the wrinkle test on a cold plate.

Skim and settle – Remove any surface scum, then let the marmalade stand for about 10 minutes. This allows the peel to distribute evenly instead of floating.

Jar the marmalade – Pour into hot, sterilised jars and seal immediately. Leave undisturbed to cool and set.