News of Britain's 'leave' vote came as a shock to many, including the financial markets, which reacted with a swift fall for sterling and an initial plunge of 8 per cent for the FTSE.

As trade opened this morning amid the breaking news that British voters – with a 72.2 per cent turnout – had voted to leave the European Union, the FTSE 100 index fell more than 8 per cent, although it regained some ground by mid-morning. Meanwhile, the pound fell from €1.31 last night to below €1.21 before picking up to around €1.24 by the end of the morning.

Contingency plans? What contingency plans?

So how are businesses across Britain and Europe reacting to this news? While the 'leave' victory has caught the whole of Europe off guard, many corporate treasurers have anecdotally been taking a wait-and-see approach.

The UK's central bank was quick to make a statement to calm fears. Bank of England governor, Mark Carney, sought to reassure markets that the UK's banks are well prepared for this outcome, having been stress-tested for even worse scenarios. He pointed out that the capital requirements for the UK's largest banks are now 10 times higher than before the 2008 financial crisis – having raised £130 billion of new capital. He said: “This gives UK banks the flexibility and liquidity they need to continue to lend to UK households and businesses.”

While Sarah Gordon, business editor at the Financial Times, writes: “Trading conditions will not change immediately, although financial market volatility and any economic slowdown could affect demand for companies’ products and services.”

Chris Cummings, chief executive of TheCityUK, a financial lobby group, told the FT that the City now needs “to focus on ensuring continued access to the single market”.

So all is well in the not-so-united kingdom?

Not really. The UK and the EU are now facing a protracted period of uncertainty. The UK's divorce from the EU will take years. While access to the single market will continue in the interim period, long-term access will be dependent on UK negotiations with the EU. These are likely to be tough and the EU has already said that it will not want to encourage other member states to consider the option of leaving.

There are other considerations for businesses. Labour costs are likely to rise if the numbers of workers from the EU is curbed. On the flip side, some business leaders complained of EU 'red tape' and they will, in a couple of years time, be free of that. However, they will also lose the right to do business freely with the EU. According to the FT, this latter point could hit the UK's financial services hard, adding that job losses will ensue: “Financial services are likely to be hit if the terms of exit end the “passporting” rights that allow banks and other groups headquartered in London to do business freely with the EU. Jamie Dimon, JPMorgan’s chief executive, claimed in June that a Brexit could mean the loss of 4,000 UK-based jobs, a quarter of the bank’s staff in the country.”