The laying of the first transatlantic cable in 1858 led to celebrations in New York like those a century later for the first man on the Moon. But it soon failed, and it was only ten years later that Brunel’s steamship Great Eastern was able to go back with a strong enough cable and a safe enough underwater route.

And as Dr Alan Walker of Edinburgh University explains, a key role in the project was played by the Scottish scientist Lord Kelvin, born 200 years ago.