Though it lies just a few miles off England’s southern coast, the curious, diamond-shaped Isle of Wight seems to exist in another era entirely. Once a beloved vacation destination for Victorian visitors, the island – still reachable only by boat from the mainland—remains a British family holiday favorite that capitalizes on the kitschy seaside charm of yesteryear. But the end of an era on the Isle of Wight is approaching. The island’s train line, whose rolling stock has consisted exclusively of former London Underground carriages from the 1930s, is undergoing…