This Monday a lorry collided with a caravan and spilled 20 tonnes of Marmite on to the M1 in Yorkshire. It's hard to think of a more English mishap and the papers lapped it up. What was basically a minor road traffic accident has, so far, generated almost 300 headlines, trended on Twitter and subjected Britons to a lot of extremely bad puns. So what is it with the English and Marmite? What dark forces are behind this rather odd obsession?