Did you know you can run diesel engines on cooking oil? Actually, I did, because it was on Top Gear a couple of months ago. What I didn’t know was that it is perfectly legal providing, unlike a bunch of chancers in Swansea, you pay duty. This opens up all manner of possibilities. Recycling fryer fat has to be a good thing (what do people do with used fryer fat? Particularly canteens and chip shops.) But then class warfare will break out, I can just see the middle classes insisting that their Volvos will only function with finest extra virgin olive oil in their tanks.