THERE has been a somewhat lamentable predominance of emotion over facts, fundamentals and reasoned analysis in the worryingly febrile atmosphere following the Brexit vote.

This has clearly not been helped by jingoistic headlines in some pro-Brexit publications, which, it appears, are being taken at face value by many.

These headlines, including a smattering this week celebrating the International Monetary Fund’s forecast of way below-trend 1.8 per cent UK growth this year, paint a far more positive picture than that portrayed this week by Chancellor Philip Hammond. Mr Hammond looks a lot of the time to be trying to put a brave face on things, so as not to spook the horses further. So he deserves credit this week for acknowledging the likely difficulties ahead, warning of “turbulence” and drawing an unappetising analogy with a “rollercoaster”.

We have had to endure another stomach-churning ride this week.

Prime Minister Theresa May set the tone on Sunday by pledging to trigger by the end of March the formal two-year process for the UK to exit the European Union. It did not take long for her declaration, coupled with fast-growing fears that the Conservatives want a ‘hard Brexit’ option even though this would jeopardise free access to the crucial European single market, to send the pound plunging against the dollar and euro.

The FTSE-100 share index rose above 7,000 points but this seemed to be down largely to the pound’s weakness, which makes the overseas earnings of London-listed international companies worth more in sterling terms.

As the pound plunged, senior independent Scottish economists warned of difficult and uncertain times ahead.

Jeremy Peat, visiting professor at Strathclyde University’s International Public Policy Institute, said: “It is a very difficult period. The uncertainties are not getting less, and the risks of a significant slowdown are still there.”

Professor Graeme Roy, director of the Fraser of Allander Institute, said of the pound’s fall: “This isn’t because we have suddenly become more competitive. It is because markets and investors see the UK as being a less attractive place with Brexit coming down the line.”

This is a time for cool heads and cold analysis, for a bit of intellectual weight to be brought to bear through a serious and sober look at the issues facing the UK. It is not a time for high emotion fuelled by an unquestioning love of Brexit or for cheap point-scoring. There is far too much at stake.

Yes, the IMF did edge up its UK growth forecast for this year to 1.8 per cent. And much was made in some pro-Brexit publications of the fact that, if this prediction and forecasts for other countries were on the money, the UK would be the fastest-growing of the Group of Seven major industrialised nations this year.

But this does not seem like much, if anything at all, to celebrate. After all, the IMF cut its 2016 growth forecast from 1.9 per cent to 1.7 per cent in July, after the Brexit vote. So, just to be clear, the latest forecast is below that before the referendum, just in case anyone thought the Brexit vote was fuelling a UK economic boom. Furthermore, the 1.8 per cent growth now projected for this year is way, way adrift of a long-term annual average for the UK that has been put at about 2.75 per cent by Bank of England Governor Mark Carney.

What seemed far more pertinent, from an analytical perspective well away from all the political and populist noise, is that the IMF this week cut its UK growth forecast for next year from 1.3 per cent to 1.1 per cent. Crucially, it emphasised this projection was “based on the assumptions of smooth post-Brexit negotiations and a limited increase in economic barriers”. These are two very big assumptions, especially given the tone from this week’s Conservative Party conference.

For context, the IMF was projecting 2.2 per cent growth in 2017 ahead of the Brexit vote, so the forecast has halved.

At least among businesses, independent forecasters and monetary policy-makers, there seems to be a recognition of the difficulties ahead.

A survey by Family Business United Scotland this week showed the economic climate is a “significant concern” for 70 per cent of family firms north of the Border, as Brexit looms.

The pro-Brexit camp has been at pains to assert, over and over again, that things in the wake of the June 23 Leave vote have not been as bad as experts had warned. However, Brexit supporters need to take a step back and realise the effects will manifest themselves over a long period, both in terms of protracted uncertainty over what happens next and the impact further out in terms of what is actually agreed in terms of single market access and other key issues.

Bank of England deputy governor Ben Broadbent said on Wednesday: “A lack of clarity about the UK’s future trading relationships needn’t result in visible, headline-grabbing closures of productive capacity. The effect is likely to be more insidious: decisions to expand, that might otherwise have been taken, are delayed.”

It is going to be a long road ahead, and it will be crucial not to lose sight of the fundamentals amid all the emotion.

If we want a clear, utterly objective assessment of the change in the UK’s economic prospects since the Brexit vote, we need only observe the pound’s tumble. In early July, having plummeted following the Leave vote, sterling hit a 31-year low against the dollar.

This week, after Mrs May’s pledge on the timescale for triggering Article 50 and amid the growing fears of ‘hard Brexit’, sterling has tumbled to new 31-year lows. The pound sank as low as $1.2621 during trading yesterday, hitting a fresh 31-year low for a third consecutive day. Sterling has hit five-year lows against the euro this week as well. Enough said.