Mark Steel introduces an extraordinary battle between two activists - a gardener and a former postman - and one of the world's biggest fast food companies. A battle over a leaflet which led to the longest trial in English history. It would bring issues like rainforest destruction and advertising to children into the mainstream. It would also be the moment our Prime Minister first comes to prominence. Ultimately, it's a story which would have connections with a dark and shameful secret at the heart of the British state - something Mark discovers he himself had been the victim of. Honestly, there are conspiracy theories less bonkers than this. Welcome to the People vs McDonald's...

Shadow World: Gripping stories from the shadows - BBC investigations from across the UK.