T he hardest part of the parachute jump, according to Capt George Lacey, is falling backwards through the air. It is Saturday and Lacey, and his squad of six plus two medics, have just leapt out of an RAF transport, 2,500 metres over the south Atlantic. “The parachute can only go forward so quickly,” he says, meaning that it has to be pulled at precisely the right moment. “So you have to turn into the wind and basically fly backwards, which is a very weird sensation, as you can imagine.” Below, with only its volcanic peak visible above the prevailing cloud cover, was Tristan da Cunha, the most remote of the British overseas territories, population 221, normally accessible only by boat, six days’ sail from Cape Town or the Falklands. A resident suspected of having coming down with hantavirus after disembarking from the ill-fated MV Hondius cruise ship last month needed urgent treatment , including oxygen. It had been deemed there was only one way to get supplies over quickly enough.…