Crush the strawberries roughly with a potato masher or handheld wand mixer in a bowl. Pare the rind thinly from half the lemons with a vegetable peeler making sure to leave as much white pith behind as possible or this will the make the strawberryade bitter. Halve and squeeze the juice from all the lemons then mix into the strawberries with the sugar.
Pour on the boiling water, stir well to mix then cover and leave to cool place. Transfer to the fridge overnight. Next day, strain if liked, and pour into a bottle, seal and chill in the fridge until needed. Use within 2 days. Serve undiluted with ice or mixed half and half with sparkling water for children.