This is a lovely basic to which you can add more or less sugar or lemons and double, halve or triple quantities as you like. If you and your children prefer, you can use still, not fizzy, water. On a hot summer day this always has been, and always will be, amazing. I like to put the sparkling water in the freezer so that it is really cold, make up the syrup (and leave it to cool) and then pour in the ice-cold water just before serving so that the bubbles don’t disappear. I think you could probably make a lovely limeade in this way, too, and soon I might try it with pink grapefruits for a brunch.