Wash the oranges thoroughly, halve them and squeeze out all the juice. Put the juice in a container to one side for the moment.

Remove as much pith as you can from the orange peel and put it into a saucepan with 2 pints of water and any pulp (not pips!).

Bring to the boil and let it bubble for 20 minutes.

Turn off the heat and leave it to cool.

Strain the contents of the saucepan through a fine sieve, pouring the orange liquid into a heatproof jug. Add enough boiling water to the liquid to make it up to two pints.

Mix in the reserved orange juice, stir in the sugar and when it's cool, put it in the fridge.

Dilute to taste.