The pound’s value against the dollar slumped by as much as 12% from £1.50 at the opening of the market to a low of £1.32 before recovering slightly to £1.37 in early trading.

Sterling’s value against the euro also fell by around 8% from £1.31 to as low as £1.20 following the announcement of the referendum results early today.

Commentators in the City of London had been forecasting a win for the Remain camp in the run-up to yesterday’s vote.

Shares also slumped on the FTSE 100 stock index, which fell initially by around 8.8% before later reducing these losses.

Shares of travel companies were among those to suffer with Thomas Cook falling by 20%, International Airline Group down by 20%, easyJet dropping by 18% and Tui AG down by 13%.

The result of the referendum has already led IAG, owner of British Airways, to issue a profits warning.

“IAG believes that the vote to leave the European Union will not have a long-term material impact on its business,” said the company in a statement.

“In the short term, however, in the run-up to the UK referendum during June, IAG experienced a weaker than expected trading environment.

“Following the outcome of the referendum, and given current market volatility, while IAG continues to expect a significant increase in operating profit this year, it no longer expects to generate an absolute operating profit increase similar to 2015.”