Natural raspberry cordial from scratch

I love making our drinks from scratch. In summer I always have a few concoctions ready and waiting in the fridge, along with cold water and ice cubes. Whoever visits is offered "tea, coffee, water or cordial?" In the midst of summer, most of our visitors choose the cordial.  We're lucky to have a prolific lemon tree and when I'm organised in winter, when the main lemon season is here, I strip