Out in the Atlantic ocean, seven hundred miles south-west of Lisbon, the lovely subtropical island of Madeira is one of the more far flung outposts of the old British wine trade. The evocative names of Malmsey, Bual, Verdelho and Sercial are now reserved for the few wines which contain more than 85% of these grape varieties. The others, mostly made from the workhorse Tinta Negra Mole, have had a tough job finding new names, a project which can hardly have helped in the battle to find new converts in the younger generation.