Ascension was an arid island, buffeted by dry trade winds from southern Africa. Devoid of trees at the time of Darwin and Hooker's visits, the little rain that did fall quickly evaporated away.

“Half of the island looks like the surface ... erupting on a beautiful golden beach,” he says. “Everyone's finding it hard to get to and from Ascension at the moment.

The Financial Times says Ascension Island, more than 4,000 miles (6,000km) from the UK, was a suggested location. What happens to migrants who reach the UK? More migrants arrive in September than ...