It can take a while for a major party to die. The Liberals last won a majority in January 1910. After the 1918 General Election a Liberal was still Prime Minister. After 1922 there were still 163 Liberals elected (albeit in two parties by then) – comparable to the Conservatives in 1997 and 2001. Doubtless many folk thought that recoverable. After 1923 it was 158. In 1924 that fell to 40. In 1929, 59. And by 1931 there were three Liberal parties, with 35, 33 and 4 seats each.

We should think of this Parliament as the Labour Party’s early 1924. It was only a few years ago that Labour was in government. Its number of seats is at a level parties have recovered from before. Few commentators are ready, yet, to declare it “over” for the Labour Party, except for those that mean Labour can’t win in 2020 and probably not in 2025. Almost all still write about what Labour needs to do to turn things around. Claims that Labour is, in fact, finished a la the 1920s Liberals are met with remarks such as “People said that about the Conservatives after 1997 and Labour after 1983, and look what happened then” or “The two-party system makes a change of parties almost impossible”.

Yet Labour very nearly did die in the early 1980s. Its greatest moment of danger was not 1983. It was in early 1982, when the SDP-Liberal Alliance led in the polls. Labour was saved by the Falklands War. Without that war, the Conservatives would probably not have polled as strongly in 1983 and the Alliance would have either entered government or come second, leading to inexorable decline in Labour. The Conservatives did not come quite so close to dying in the early 2000s, but an only slightly better-organised Ukip might have encouraged a significant number of defections if Michael Howard had done only slightly worse in 2005, which could well have happened had the Iraq War gone better.

The sense that Labour and the Conservatives are immortally entrenched as the two main UK parties is rather like my youngest son’s argument when I tell him to tie his shoelaces lest he trip and fall into the road. He counters: “But I’ve never done that.” I say: “Indeed not – that’s why you’re not dead. You’ll only do it once.” Labour or the Conservatives will only die once. Folk saying “It’s not happened in the past” proves nothing.

If there were a single moment to point to when Labour died it was probably the Scottish Independence Referendum. Labour has never held a majority in a UK General Election without at the same time holding a majority in Scotland. The SNP has now eviscerated Labour there and with the Conservatives now a clear second, it will be Conservatives that form the focal point for future opposition to the SNP. Labour has no way back.

Once it grasped that that had happened – once it collectively sensed that its era as a party of government was over – Labour gave up the collective ghost by choosing Jeremy Corbyn. It was not the election of Jeremy Corbyn that destroyed Labour’s chance of governing again. Labour chose Corbyn because it knew it already had no chance of governing again, no matter whom it chose, so it felt it might as well choose someone it regarded as reflecting its deep-down beliefs. (As it happens, I don’t think Corbyn actually reflects Labour’s core beliefs, but that’s another story…)

Labour would have faded away, whomever it chose. It’s not even obvious that Corbyn will do worse, electorally, that his alternates, in this era of populist anti-establishment sentiment. But he will lose – terribly. Labour is a zombie party. It is already dead, but marches slowly and comically about, representing the occasional threat of removing the brains of the unwary.

What will replace it, though? Many folk assume that must be some kind of new split – an SDP for our generation. It’s hard to grasp what the electoral appeal of that would be supposed to be in our age. The annihilation of the Liberal Democrats was indeed partly because their “soft Labour” brand was tarnished by coalition with the Conservatives, partly because of tuition fees and partly because their raison d’etre was ended with defeat in the Alternative Vote referendum. But it was also because that kind of thing isn’t wanted any more. It’s not just Tony Blair that is unpopular. His whole ethos is seen as failed, on both left and right. George Osborne and Michael Gove were almost his last important fans. Labour vs neo-SDP would just be like the multiple splits in the Liberals in 1931 – the death spiral of decline.

Ukip, then? If Remain had won the referendum, I think politics might well have re-aligned between those seeking to leave the EU and those remaining. I doubt Ukip would have been the brand chosen but its might have been an important part of the Leave coalition. Now, though, it seems more likely to be an element in Labour’s decline – eating Labour seats in the North or splitting the working class vote to let the Conservatives in. It’s near-impossible to imagine the British electorate choosing Paul Nuttall as a Prime Minster.

No. Instead I think we must assume that tomorrow’s new two parties will both come from the Conservative Party. By around 2030 or 2035 there will be some new split over some issue we cannot even imagine today – probably a foreign policy or constitutional question; these things usually are.

Some 25 or even only 20 years of Conservative hegemony will be alien to the British political system. It requires plausible opposition to be healthy. The Conservatives will not get it for a long long time. In the meantime there will inevitably be the mistakes that come from a lack of scrutiny. Let’s hope those errors aren’t ultimately too bad.