UK markets shudder after Brexit vote, sterling hits 31-year low

By Jamie McGeever and Patrick Graham LONDON (Reuters) - Sterling plunged to its lowest in three decades and the value of London's big banks sank by the most since the 2008 financial crisis as Britain's shock vote to leave the European Union triggered turmoil on global financial markets on Friday. The damage to London's stock market eased as the day wore on, helped by expectations the weaker pound would help many UK companies and by the Bank of England's promise of 250 billion pounds of extra sup