The UK as a political entity is notoriously difficult to change. Progress is often in inches not metres, and in small drips rather than flash floods. Thus the House of Lords is reformed but unelected, and the House of Commons is only elected by an unreformed system. The Scottish parliament and its sister assemblies in our neighbouring nations are the exceptions that prove the rule.

However, within 24 hours of calling a general election, Theresa May managed to dump two of the most recent reforms to political practice in the UK. They were modest and had only made a small scratch in the mould of Westminster politics, but they were progressive – and have now been junked.

When the 2017 election story is written, Corbyn's act of self-destruction will be one of the most difficult to explain

The first was the prime minister’s circumventing of the Fixed-term Parliaments Act. This measure introduced by the coalition government was not particularly principled in its origins. It existed to give comfort to the Liberal Democrats, who were fearful that they would be stabbed in the back by David Cameron exercising the traditional prime ministerial prerogative and dashing for an election. In the event, the Tories waited until 2015, and George Osborne stabbed them in the front instead.

However, in limiting that prime ministerial power, the fixed-term legislation did allow an element of rebalancing the UK power structures, and indeed the relationship between parliament and the executive.

Of course, May has been greatly assisted by the Her Majesty’s loyal opposition in achieving her aim of restoring the ancien régime, when elections took place at prime ministerial convenience.

All Jeremy Corbyn had to do was to instruct his troops to sit on their hands last Wednesday, and the prime minister would have been left high, dry, and short of the two-thirds majority of the whole house she required to have her way.

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Even if for some insane reason he still wanted the election, the Labour leader could then have moved a motion of no confidence in the government. This would have left May with the unpalatable choice of having to back it to have the election she craved, or move her own motion of no confidence in her own government. When the full story of the 2017 election is written, this act of self-destruction by Corbyn will be one of the most difficult to interpret or explain.

Indeed, if he had so wished, Corbyn could have used his leverage to prevent May junking a second constitutional reform. In the first days of the 2017 contest she has tried to end leaders’ television debates.

The idea that such debates would and could be refused in the 21st century is staggering. They have been part of the Scottish political scene since the Usher Hall debate of 1992, but were introduced in 2010 to Westminster elections only because Gordon Brown was a prime minister who needed a game-changer to have any hope of retaining his position – and David Cameron was caught having previously campaigned for them. But whatever the motivation, the 2010 debates were a small step forward in public accountability.

In the end, both Cameron and Brown were hoist on Nick Clegg’s petard, and the result was a Lib Dem performance strong enough to enable a coalition government. As an aside, the disastrous refusal by Tim Farron, the Lib Dem leader, to rule out another coalition with the Tories in the debate on Wednesday – caught in a pincer movement by the SNP duo Stewart McDonald and John Nicolson – is the most underrated blunder of the campaign so far. When will they ever learn?

It was generally assumed that once the precedent was set, there would always be television debates in elections. However, May’s refusal to take part can be explained in two words – Lynton Crosby.

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She has hired Cameron’s “Wizard of Oz”, that master of the darkest of political arts. Lynton’s highly paid instruction would be simple, but probably delivered to the vicar’s daughter with his usual expletives deleted. It would be something like “You are 20 points ahead, prime minister – take no risks whatsoever”. And so two modest reforms to the unwritten glorious constitution have gone in the first two days of this election campaign – which leads to a wider lesson.

This is a prime minister who finds dissent inconvenient, even irritating. A case in point is her extraordinary diatribe outside No 10, aimed at all the opposition parties for opposing. This posed as the pretext for having an election she solemnly pledged seven times not to call.

Theresa May is facing the weakest opposition in living memory. Still she is not satisfied. Total compliance with her way is required – or else. We have six weeks to demonstrate that resistance is not futile and Scotland will not bend the knee to prime ministerial diktat.

In doing so, the SNP will be performing a service to Scotland certainly – but also to all those who believe in progressive and diverse politics across these islands.