The pound has fallen to a 31-year low against the dollar as markets reacted strongly to the Leave campaign taking a clear lead in the EU referendum.
With 270 out of 382 results declared, the pro-Brexit side was in the lead by more than 600,000 votes - and experts predict the gap to widen further.
A strong position for the pound earlier, after polls suggested a narrow lead for Remain, collapsed in spectacular fashion as traders reacted to the Leave lead.
The Associated Press reported the crash in value for Sterling as one of the biggest in history in a single day, plummeting from aroun $1.50 to below $1.35. It is the first time it has done so since 1985.
If confirmed, a vote to leave will have an impact on markets across the wider EU.
Nigel Farage, the Ukip leader, said he wanted to see the 28-nation bloc brought down by the UK result, in what was in tone a victory speech to supporters.
David Cameron is now facing clamours to stand down, as a Prime Minister who campaigned passionately for the losing Remain side.
Mr Farage said he should resign "immediately", while even his own Conservative MP Jacob Rees-Mogg told the BBC he expected a general election by the end of the year.
