This is hard-core London, and just before Farringdon station you will be able to glimpse the vast steel pipe that carries what was the Fleet River and is now the Fleet sewer over your head.

The Fleet looks safely contained now, although you never know. It surprises me that no terrorist has made common cause with the surly and embittered Fleet, which, in Peter Ackroyd's words became 'a river of death' as it sidled through the meanest streets of London en route to the Thames.