Revolutions are curious beasts. Those who initiate them, all too often, are not their beneficiaries. In many cases they are some of the chief casualties. This is scarcely an original observation, Jacques Mallet du Pan wrote in 1797 that “revolution devours its children”, but it is a prescient one. Starting a revolution is rather like firing a rocket into the air. You release a huge amount of energy, but can never be entirely certain as to where it will land.

Brexit, according to Nigel Farage, is revolutionary. Last year he described it, along with the election of Donald Trump, as the “beginning of a global revolution”. A victory over “the multinationals” and “the big merchant banks”. Boris Johnson was similarly dramatic terming the referendum date Britain’s “independence day”. Both Leave and Remain supporters generally agree, as they do on little else, that it’s a seismic national occasion. We can all accept the rocket has been launched, even as we continue to dispute its destination.

If Brexit is a revolution then there is no shortage of potential hijackers waiting in the wings. Those who would utilise the energy and confusion it has created to take the country in an entirely different direction. Chief amongst these is Labour Shadow Chancellor John McDonnell, the first person to hold that office in the modern era whose commitment to Parliamentary democracy itself seems at best conditional.

McDonnell is open about the opportunity he sees in a botched Brexit. Last Monday he told the Labour Party Conference in Liverpool that “the greater the mess we inherit, the more radical we have to be; the greater the need for change, the greater the opportunity we have to create that change”.

When asked by The New Statesman in 2006 to list his main political influences McDonnell replied “The fundamental Marxist writers of Marx, Lenin and Trotsky”. I mention this because McDonnell is far from the first radical leftist to see disaster as a potential ally. Prior to WWI the Second Socialist International, an umbrella group of predominantly European socialist parties, had a plan to stop any “imperialist” war breaking out between the great powers. If such a conflict seemed imminent, they decided, the workers in each implicated country would go on strike until the Governments were forced to back down.

In practice of course this didn’t happen. Most socialists ended up supporting the war efforts of their respective nations. A smaller group held true to the principles of the Second International and condemned all warning parties. But a handful, most notably Lenin, went much further. They adopted the policy which became known as revolutionary defeatism. This meant actively hoping their own nations were vanquished, celebrating every failure, in the hope that this would lead to revolution.

In Russia it worked. As the economy suffered and the establishment were discredited something that would have seemed crazy a few years before – the state apparatus being seized by a bunch of exiled Bolshevik fanatics who had spent the past decades wasting away in Swiss cafes – sneaked into history.

McDonnell’s policy is revolutionary defeatism for the 21st Century. Hope the Brexit process turns sour, the more damaging the better, and in the process discredits or destroys the Conservative Party, the chief institution standing between Corbyn and power. It could work. It’s not that Brexit will inevitably fail. It could be a great success. But in the short-term it will invariably cause disruption, potentially severe in some sectors, and that will give the Corbynites the window they need.

It is highly likely that the next British Government will consist of, or at least be based around, either the Conservative or Labour parties. Thus a blow to one is a gift to the other. If the Conservative Party, and British right more generally, loses its reputation for economic competence even temporarily it’s the left that will gain. And at present ‘the left’ means the Corbynites.

The Brexiteers have reason to curse their luck. After years, even decades of toil they finally acquired first their referendum and then Leave vote at a time when two other movements are within touching distance of dramatically transforming the UK. The first, as already outlined, is a radicalised Labour Party. A Party which, for the first time in its history, owes more to Marxism than Methodism. The second is the Scottish nationalists who came within a whisker of finishing Britain as a political unit in 2014 and have every intention of finishing the job. Sturgeon clearly thinks that an ugly Brexit process, even if only temporary, could provide them with their moment.

To be clear, this isn’t an argument for Brexit to be delayed or stopped. The leave campaign won a binding referendum, and nothing has or can do anything to change that. But it is an argument for caution. The Corbynites can smell power. John McDonnell clearly thinks a botched Brexit could push them over the line, with all the consequences that would entail. We would be fools not to listen. Nigel Farage is right about one thing – Brexit is revolutionary. And revolutions rarely follow the script prepared by those who initiate them.