Nobody would know from the outside of Marriage's Mill quite how amazing it is on the inside. Situated in an industrial park just outside Chelmsford in Essex, the mill produces flour and animal feed from the waste products of the flour production. One building is built around a complex system of machinery and pipes that suck grains of wheat up and down, in and out, shake them all about, and grind them into flour. Then the waste from this is transferred to a second building that houses what might best be described as looking like a miniature indoor oil rig - grinding, humming, shaking and trembling with activity, turning that waste into animal feed.