The rescue came a day after the same crew went aground on the Foulness Sands without charts, flares or a VHF radio, and reported themselves lost.

BBC: Coastguard plea after Canvey to Harwich voyage rescues

From an initial insubstantial trickle it has grown to a world-class waterway, and as it spreads to 29km wide between Whitstable and Foulness Point, the Thames is heavy, not only with water, but millennia of history.

BBC: Following the Thames: A source-to-mouth guide