UK PLC breathes easy again after Scotland's no vote - but for how long?

Relief rather than euphoria. That was the instant response in the financial markets to the Scottish referendum vote.

Relief that they had been spared months, perhaps years, of wrangling about what currency Scotland might use. Relief that the risk of a bank run had been avoided. Relief that there was unlikely to be a flurry of announcements by companies that they were packing their bags. Relief, above all, that it was not going to be Black Friday.

As a result, the pound continued the rally that had started on Thursday once the City of London became convinced that the strong advances by the yes side in the last weeks of the campaign had been halted in the final 48 hours before the poll. Sterling was up against the US dollar and at a two-year high against the euro. Shares in London rose in early trading.

But while it was easy to explain the relief, it was also easy to explain the lack of euphoria. Sure, the knee-jerk reaction to the result was that the worst case had been averted. There would be no queues of depositors outside branches of Scottish banks, no need for emergency injections of cash from the Bank of England, and no dumping of the pound by foreign investors. A panic averted is always good news for markets.

The bad news was that many of the issues raised by the referendum had not been resolved once and for all – merely deferred to another day. On past form, that will weigh on markets once they have had a bit of time to reflect.

Issue No 1 is that the result is close enough to make another referendum a possibility, despite the Scottish Nationalist party leader, Alex Salmond, saying that a no vote would mean it was off the agenda for a generation.

Financial markets are spooked by political risk, and there will be plenty of that in the months ahead: a possible backlash by Conservative MPs against the new powers to be granted to Scotland; the debate over devolution to Wales, Northern Ireland and the English regions; and the possibility of a change of government at Westminster next May.

Markets are already starting to fret about the referendum on Britain's membership of the EU that would take place in 2017 if the Conservatives win a majority in next year's general election.

Issue No 2 is how companies based in Scotland react to the news. Many of them had contingency plans for moving operations south of the border in the event of a yes vote. They may decide, given the closeness of the referendum, to go ahead with those plans.

This will not be a case of rapid capital flight; rather a drip-drip effect over the coming months and years. Lloyds Banking Group said it was committed to having a significant presence in Scotland. That appears to fall someway short of a full-throated commitment to remain registered in Edinburgh.

Issue No 3 is what the vote means for interest rates. Uncertainty over Scotland has been weighing on the Bank of England's monetary policy committee: the risk of a recession in Scotland has been removed and some of the investment decisions that have been mothballed in recent months will proceed. The result makes an increase in the cost of borrowing marginally more likely.

The final issue is that the referendum has highlighted some of the weaknesses in the UK economy – in particular the importance of the North Sea oil in disguising the weakness of the balance of payments caused by the decline of manufacturing. Without oil and gas, the UK would be running a current account deficit of 7% of GDP. Even with the help of the North Sea, the gap stands at 4.5%, extremely high for a country in the early stages of an economic recovery.

The prospect of an independent Scotland taking control of 90% of North Sea reserves would undoubtedly have sent sterling into a tailspin. Even though that threat has now been removed, the size of Britain's trade gap means the upward movement in the pound is limited. Sterling is vulnerable to bad news – be it a slowdown in growth, problems in the eurozone or a widening current account deficit. Once the dust has settled, it is likely to fall back.