We must act, said Boris Johnson on Tuesday, “like any wartime government”. The measures to control the population, he added, were “unprecedented since world war two”. Rishi Sunak, speaking later, announced, “We have never, in peacetime, faced an economic fight like this one.”

The second world war remains the foundation myth of modern Britain. Invoking it is a familiar default setting in British party politics. It has a Conservative version, embodied in Churchill, with whom Johnson compares himself. And it has its Labour version, in the form of veneration of Attlee and the post-1945 welfare state. The war still suffuses much of the national culture. It can sometimes be an inspiration. But it can sometimes, indeed more often, be a curse.

The playbooks of this peacetime effort will have striking comparisons with the playbooks of distant wartimes

That is not true today, however. Johnson and Sunak are right to compare the coronavirus crisis with the wartime emergencies of the 20th century. We are all doing it. These are the only meaningful reference points for the totalising crisis that suddenly faces this and other nations. Government and society are now in a very new place. As Johnson put it this week: “The state is asking people to make very considerable changes to their lives. And it is only right therefore that the state should stand behind people as they make those changes.”

It is 75 years since a British prime minister talked in such terms. For most of the past 50, such remarks were effectively anathema, especially in the Tory party. And yet, although the transformation of the role of government in less than two weeks has been genuinely jaw-dropping, this is not yet the same as a wartime crisis in some very important ways. These differences need to be understood, not least because it may help to avoid the error, long familiar in military strategy, of mistakenly setting out to fight the last war rather than tackling the one that we actually face.

Start with the blindingly obvious. Britain in 2020 is not the Britain of 1939, let alone the Britain of 1914. We are an infinitely more connected, more individualistic and more informed society today than we were then. These realities cannot be ignored, though they may change. They will set the initial terms of what is politically possible. The playbooks of this peacetime effort will have striking comparisons with the playbooks of those distant wartimes, but there will be striking differences too.

You can see this in Johnson’s reluctance to prohibit things that will soon need to be stopped. Much of that will surely change and be tightened, and rightly so. The same is true of the incomplete character of Sunak’s huge spending spike. Johnson may say that the state is standing behind society “through thick and thin” but the state is not yet standing behind households, behind renters and the self-employed. At the height of the second world war, public expenditure topped 80% of national income. We are nowhere near that figure yet.

Johnson’s Tories will also take exceptional powers this week, rather as Asquith’s Liberals did in 1914 and Chamberlain’s Tories did in 1939. But those wartime powers were truly draconian from the outset in ways that Matt Hancock’s emergency coronavirus bill is not – at least for now. Hancock’s bill is certainly remarkable. It allows police and immigration officials to detain people suspected of carrying the Covid-19 virus, permits ministers to close transport hubs and ports, and gives government the power to ban and close places such as schools that, up to now, have mainly stayed open.

But this is as nothing when compared with past wartime powers. The Emergency Powers Act of 1939, for example, gave ministers sweeping authority to govern through regulations with no parliamentary sanction whatever. Any act of parliament could be amended or suspended on a minister’s say-so. Food, fuel, pharmaceuticals and clothing were controlled by the state and strictly rationed. Ministers could intern anyone whose detention was thought expedient on grounds of public safety or the defence of the realm. Censorship of the media was effective and was broadly accepted by the media themselves.

In both the world wars, moreover, it soon became unsustainable for the single-party government which presided over the outbreak of war to remain in power without forming a national coalition. Asquith brought the Tories and Labour into government in May 1915 and even offered a cabinet post to the Irish Nationalist leader John Redmond. Formal opposition in parliament ceased, and there was a byelection truce. Churchill did much the same in May 1940, when Labour agreed to serve under him.

Are such things conceivable as the coronavirus crisis progresses? Certainly they are. But much will have to change on the ground and in government before there is even a chance of them happening. It is hard to imagine the media agreeing to withhold statistics on the progress of the pandemic in the national interest as they did with casualty figures during the world wars. A form of rationing has now begun in the wake of panic buying, but it remains devolved to a cartel of supermarkets, and confined to a small number of goods. The over-70s do not yet risk arrest for buying a pint in a pub.

Yet this is unquestionably a national crisis. But it is just the start. We are still in the phoney war, it-will-be-all-over-in-weeks phase. In August 1914, most governments assumed the existing armed forces would do all the fighting and that civilians would not be much involved. They were wrong. By the same token, it is possible that Johnson and Dominic Cummings still imagine they will be able to spin their way through the crisis and resume their interrupted election agenda. But they would be wrong too.

Politics and the nation are still adjusting to a systemic shock. Johnson is not a unifying figure, though he is trying hard to be one. Nor are many of his ministers or advisers. Who trusts Priti Patel with our liberties? Trust in all politicians is low. The country has been deeply divided by austerity and Brexit. That’s why, just as in 1915 and 1940, it may eventually feel inevitable for Labour and even the SNP to be brought into a governing coalition in some way. This may be a wartime government but, as Asquith and Churchill found out and Johnson may learn, the politics that emerged from the war may be very different from the politics that preceded it.

• Martin Kettle is a Guardian columnist