BORIS Johnson is making a big, big noise about Brexit.

We should not be surprised. The volume is in keeping with his political style, which appeals to some and appals others.

And it also seems in keeping with what looks set to be a rambunctious Conservative Party leadership contest, with much thumping of tubs.

Already we have had not only the usual, tiresome jingoistic claptrap about Brexit but also dangerous deadlines and ultimatums from the likes of Mr Johnson and Dominic Raab. As if that were not enough, we have had frankly horrifying talk (from Rory Stewart) about compulsory National Citizen Service for teenagers, many of whom are already having to pay a high price for the hopeless economic policies and Brexit folly of the Conservative Government.

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These young people face the prospect of having their future mobility hampered seriously by the Brexit stupidity. They face huge hurdles in getting on to the housing market, and have to endure the insecure gig economy, in a world in which the Tories have presided over huge erosion of employment rights.

Yet Mr Stewart would have these young people further disadvantaged by having to give up a month of their lives, with all the attendant disruption, for the oh-so-Tory desire for some form of national service. We have Mr Stewart chanting about “purpose” and “character”.

Young people have plenty of purpose and character, and they will need both in spades to navigate their way through the economic and social mess created for them by the Tories. Things are bad enough, with a pressing need for the UK to tackle poor productivity by upskilling, and the eventual pensions timebomb that will be faced by young people when they finally get to retirement, without Mr Stewart’s additional hurdle at a key point in teenagers’ lives. Enough about Mr Stewart’s big Tory idea though, and back to Brexit.

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Mr Johnson and other hard-line Leavers in the Tory leadership contest should take a good look at the latest gross domestic product data from the Office for National Statistics. Brexit voters might be excited by Mr Johnson’s pledge that the UK will leave the European Union on October 31, with or without a deal, but it is important to cut through the awful noise of all that tub-thumping and reflect on the terrible reality of such a situation.

The huge uncertainty created by the move towards Brexit has already hit the UK economy hard. However, the damage that would be done by Mr Johnson’s proposal of leaving the EU without a deal if there is not one by October 31 would be on a whole different level. He only needs to look at his own Government’s forecasts to see that. Mr Johnson seems to have this idea that somehow the EU will blink, roll over and give in to his Brexit demands if he becomes prime minister with his deadline. But it should be clear to everyone by now that this is not going to happen. More importantly, given he seems in favour of a hard Brexit with single-market departure, even if there were an agreement with the EU over such an ill-judged exit it would in any case do little to mitigate the damage to the UK.

Many Conservative MPs seem to be lapping up Mr Johnson’s orations on Brexit at the moment, as he rides high in the popularity stakes. Scotland’s First Minister, Nicola Sturgeon, in contrast believes the prospect of Mr Johnson, or Mr Raab or Michael Gove for that matter, becoming prime minister is “pretty horrific”. Given the economic mess created by the Brexiters, and Scotland’s big majority to stay in the EU in the 2016 vote, most people north of the Border would seem likely to be in tune with Ms Sturgeon on this point, rather than with the swathes of Boris-backing Tory MPs.

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The big problem for Mr Johnson is that, while other EU countries might be affected to some extent by a no-deal exit by the UK, the problems that such a scenario might throw up for them will be minuscule relative to what mighty Blighty will suffer.

Mr Johnson has claimed MPs will “reap the whirlwind” if they block Brexit.

The phrase “reap the whirlwind” has its roots in the Book of Hosea in the Old Testament. Chapter eight says that those who sow the wind “shall reap the whirlwind”.

Taking the proverbial phrase to which this passage gave rise and putting it in the context of Brexit, the ill-wind that is hampering the UK’s economy and society was whipped up by the Leave campaign. The trouble is not, and has not been, created by MPs trying to protect the UK economy and, crucially, people’s living standards, by trying to stop a no-deal or otherwise damaging hard Brexit, or by endeavouring to prevent the folly altogether.

Figures published this week by the Office for National Statistics show UK gross domestic product fell by 0.4 per cent month-on-month in April. The National Institute of Economic and Social Research think-tank forecast, in the wake of the figures, that UK economic output would fall by 0.2% over the second quarter.

Part of the UK economy’s weakness in April arose from temporary shutdowns implemented by car manufacturers in anticipation of the previously planned March 29 Brexit date. UK motor vehicle production tumbled by 24% month-on-month in April, the sharpest fall since comparable records began in January 1995. But the economic weakness was far, far more broadly based, with services output stagnating month-on-month and the construction sector contracting by 0.4%. Including the Brexit-related weakness in car production, overall UK manufacturing output tumbled by 3.9% month-on-month.

Scottish Chambers of Commerce chief executive Liz Cameron warned in the wake of the ONS figures that the well-being of the nation’s citizens was reliant on an end to Brexit-fuelled uncertainty.

Ms Cameron said: “The drop in GDP in April...does not bode well for Scotland’s economic fortunes. However, it does confirm what businesses have been saying with increasing urgency for years now – the well-being of Scotland’s citizens and the health of our economy now relies on the uncertainty caused by Brexit to end.”

For the avoidance of doubt, the business community does not want the kind of end to the uncertainty that Mr Johnson is threatening. The last thing that hard-pressed businesses need is for their worries about a bad outcome to be replaced by the crystallisation of their fears.