Professor Adam Tomkins, who left Holyrood last year after one term to return to work at Glasgow University, wrote in a column for the Herald newspaper that the Tories’ time in power “is up”.
“What we are witnessing right now is not only the Conservative Party trashing its own brand: it’s the Conservative Party trashing the economy,” he wrote.
The Chancellor unveiled plans last week that will scrap the top rate of tax and cut the basic rate to 19p in the pound – plans that saw the pound fall to its worst ever level against the dollar and the International Monetary Fund (IMF) appeal to Mr Kwarteng to reverse course.
But Prof Tomkins said tax cuts should come in a strong economic environment, rather than to spark growth.
“The newfound Trussonomics says that we cut tax first,” he wrote.
“It is profoundly unconservative.
“A conservative would grow the economy first; a conservative would tackle the deficit first; a conservative would get public spending under control first and, only then, only once growth has returned to the economy, would a conservative cut tax.
“Evidently, the markets agree.
“The hammering that the pound is taking not only against the dollar but, even more worryingly, against the euro, is the strongest possible sign that the markets don’t buy the newfound recklessness, the dogma that you can tax-cut your way to lower public spending.”
And, he said, “voters also agree”, as Labour surges ahead of the Tories in the polls.
Prof Tomkins went on to say there was no majority in the UK, or even in England, for the tax plans, adding “yet this is the dogma the newly unelected government are now imposing on us”.
But the former MSP hit out at Labour’s plans for the union, which he described as “cacophonous drivel”.
“It is a truism that oppositions do not win elections: governments lose them. And it is true also that the 2024 general election will turn on the economy, and not on the constitution,” he wrote.
“All of which is just as well for the Labour party because, in contrast to Rachel Reeves’ prudence on the economy, the noises coming from the party leadership of late on how Labour will save the Union, reform the constitution, abolish the House of Lords, and reboot devolution are cacophonous drivel.
“They are drivel not because there is no case for significant constitutional reform in the UK, they are drivel because to think this is anything to do with “saving the Union”, or to aim your fire at the House of Lords whilst overlooking much more serious weaknesses elsewhere in our democracy, is both to misdiagnose the problem and to prescribe the wrong solution.”
Former prime minister Gordon Brown has been tasked by the party with drawing up plans for reform of the union, which reports indicate could include the abolition of the Lords.