It was no surprise the pound plunged to fresh 37-year lows below $1.09 and the UK’s FTSE-100 share index finished 140.92 points or 2% lower after Chancellor Kwasi Kwarteng’s mini-Budget yesterday.

There is surely much cause for worry about what was delivered. Moreover, the Government’s decision that the independent Office for Budget Responsibility should not publish economic and borrowing forecasts yesterday, incorporating the measures unveiled, likely jangled nerves further.

The speech was dubbed “The Growth Plan”. However, while it set out the ruling Conservatives’ desire for a trend rate of annual economic expansion of 2.5%, there was precious little by way of a plan to achieve this very tall order. Curiously, though not surprisingly given the Tories’ puzzling ideology, the growth aim was wrapped up presentationally with the abandonment of the planned rise in UK corporation tax from 19% to 25% from next April. This planned increase had been announced by former chancellor Rishi Sunak in his March 2021 Budget.

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The Treasury’s press release trumpeted: “Corporation tax rise cancelled, keeping it at 19% as Government sets sights on 2.5% trend rate of growth.”

This cancellation, for the avoidance of doubt, is a very expensive move indeed.

Mr Kwarteng declared: “This will plough almost £19bn a year back into the economy. That’s £19bn for businesses to reinvest, create jobs, raise wages, or pay the dividends that support our pensions.”

Recent history signals the move will be highly ineffective, as well as expensive.

After the Conservatives came to power in 2010, they cut the main corporation tax rate from 28% to 19%, in stages. Former chancellor George Osborne seemed to view this huge reduction as a crucial step in realising his vision, set out in his March 2011 Budget, of “a Britain carried aloft by the march of the makers”. This vision proved to be a fantasy, as the economy performed dismally even before the difficulties were exacerbated by Brexit and then eventually also the coronavirus pandemic.

UK business investment consistently proved extremely disappointing.

So we should treat with great caution Mr Kwarteng’s view of how the £19bn a year will be deployed.

Even when corporation tax was at 28%, the UK was perfectly competitive in an international context.

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Mr Kwarteng could have better characterised the £19bn as the amount of tax revenues that will be lost each year as a result of his reversal of Mr Sunak’s plan. This would have been far more apposite, given the degree to which financial markets appear to have been spooked by the huge increase in government borrowing required to fund the measures announced and confirmed yesterday.

The support on energy prices, to limit the surge in bills for consumers and businesses, is very expensive. Mr Kwarteng estimated the cost at £60bn over the next six months, and the assistance for households lasts for two years. However, this support is absolutely necessary, crucially so people can afford to heat their homes but also in terms of bolstering consumer spending by ensuring disposable incomes are not wiped out or reduced severely by colossal energy bills. Support on energy for businesses is also vital, to ward off the threat of collapse and job losses. The very direct boost to the economy from the help with energy bills is crystal clear.

Abolishing the 45% top rate of income tax is, in contrast, expensive and unnecessary, and will do very little to support demand given high earners will surely save much of this windfall from the Tories.

Amid the cost-of-living crisis, with demand under severe pressure from surging interest rates, still-huge energy price increases and rampant general inflation, the corporation tax rise reversal and top income tax rate abolition are bizarre ways to respond, if the UK Government is actually interested in stimulating growth.