UPDATE 8-UK markets shudder after Brexit vote, sterling hits 31-year low
* Biggest fall for the pound in free-floating era
* Markets price in cut in Bank of England interest rates
* BoE pledges of extra funds, foreign currencies prop up FTSE
* Bank shares down (Recasts with FTSE recovering to gain on the week)
By Jamie McGeever and Patrick Graham
LONDON, June 24 (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 support.
But shares in Royal Bank of Scotland and Barclays fell by around 18 percent and, even with an afternoon recovery, sterling's fall was the biggest since the system of free-floating exchange rates was introduced in the early 1970s.
Major bank analysts predicted the currency would fall further in the months ahead, as financial investors price in the long- and short-term uncertainties unleashed by the Brexit vote and the scale of the damage to Britain's economic prospects. Continuación...