On (and in) the Thames

“A few years ago, I decided to walk on the foreshore of the Thames from Battersea Park as far to the east as I could. I had observed over the years that, at especially low tides, quite large areas of hardened mud were exposed; these were either studded with pebbles and flints, or gave way to chunks of concrete slipway, or elided into true shingle. Naturally, being the sort of man I am, I hadn’t made a comprehensive survey of either the littoral or the tide table, so I soon found myself wading...