Libertine is a small Essex sparkling house with a taste for the unbuttoned: a dry, salmon-pink rosé brut made by the traditional method and aged on lees for a biscuity depth that belies its price. Essex has become one of England's most talked-about wine counties, its low rainfall and warm, dry summers ripening fruit that Sussex would envy. Libertine makes the most of it, with rather less reverence than most.