Beat the eggs, sugar, juice, water and rind in a bowl. Chop the butter roughly and put into a saucepan. Add the egg/lemon mixture and heat gently, stirring constantly, until the butter has melted.

Continue heating gently, stirring constantly to keep a smooth consistency, until the mixture thickens sufficiently to thickly coat the back of a wooden spoon. Don't allow to boil.

Pour into small jars while still hot and seal immediately.