Anyone who ever realised with horror that they were driving on the wrong side of the white line will understand the need for road rules. Ever since 1835, the British have been bound by law to keep to the left on public highways. But although Queen Victoria's reign saw a rapid increase in shipping, it was nearly half a century before similar regulations applied to rivers.
The Thames in particular was a busy highway, with vessels of all sizes making their way to and from the Port of London. Increasingly, these were powered by steam and built of iron. Yet each was at liberty to follow whatever course its master fancied. Given that the Thames had strong tides, fast currents and bends, this was a recipe for disaster.
On the evening of September 3, 1878, disaster struck - a calamity that, according to one contemporary, "shook Great Britain like an earthquake, and sent a shudder vibrating through the world".
Two ships were involved: the Bywell Castle, a steam collier of 890 tons, and the Princess Alice. This little paddle steamer was an eighth of the size of the collier, but she had hundreds of passengers on board - Londoners returning from a day trip to Gravesend.
Later, the captain of the Bywell Castle recalled seeing the Princess Alice about to cross his bow. He had altered course to pass safely astern of her, but at that precise moment, the captain of the Princess Alice, unaware of the collier's intentions, had also changed direction.
Within four minutes of the collision, the little paddle steamer was lying in two halves on the riverbed. And in the minutes that followed, 640 of her passengers lost their lives in the dark, foul waters, filthy with raw sewage from the nearby Northern Outfall. After 10 weeks of investigations, both captains were heavily criticised for their poor judgment.
In 1880, as a direct result of the disaster, new regulations came into force. From then on, steamships had to pass each other on the port side, for that was the rule of the road.