Perhaps we should let Labour go for a while. As a party of government, it has left the electorate behind to go on a voyage from which it may or may not return. A Labour government in 2020 is unlikely, although you never know, and may even be undesirable. Right now, every column about Labour’s internal arguments runs the risk of being an indulgence or just slightly irrelevant.

One day, this may change. But for the moment, only two parties are shaping this country: the SNP and the Conservatives. This is where British politics in 2016 will be fought out.

Internal SNP and Tory arguments are anything but irrelevant. Non-aligned voters have a big dog in these governing party fights, even if we would never think of ourselves as nationalists or Tories. On almost every one of these issues we need the more hard-headed, generous-spirited and modern-minded to win the argument against the less.

George Osborne warns UK economy faces 'cocktail of threats' Read more

None of these arguments affects the rest of us more immediately than the Conservative argument about Europe.

There is much to criticise in David Cameron’s approach, above all the generational failure of the post-Heseltine Tories to evolve the kind of solid warts-and-all case for the EU that Cameron and his supporters are now having to improvise at the eleventh hour as the referendum nears. But it matters hugely, all the same, that the prime minister wins rather than loses this argument.

This is also, I think, the insufficiently understood context in which to analyse George Osborne’s remarkably downbeat speech in Cardiff earlier today and the new tone of the interview that the chancellor gave on BBC Radio 4’s Today programme before travelling to Wales.

On the face of it, Osborne’s speech was about the economy, with striking warnings that 2016 could mark the beginning of a decline for Britain if the country fails to adapt to a “dangerous cocktail” of risks including the Chinese slowdown, fresh tensions in the Middle East and the continuing fall in the price of oil. The fear-filled language was in startling contrast to the optimism of November’s autumn statement. The economic message, said Osborne, was not “mission accomplished” but “mission critical”.

On one level all this is simply a statement of the economically obvious. China’s slowdown since last summer is roiling the stock markets and the currency exchanges. The world oil price is at a 12-year low. The US has begun to raise interest rates after a long period of low to non-existent rates; Europe and Britain seem likely to follow this year. Growth has been revised down, and hopes that the UK economy may emerge rebalanced and less credit-greedy from the post-crash consolidation have proved illusory.

Yet these trends have not emerged over Christmas. They were well established in the final quarter of 2015 and before. China was already struggling, oil and commodity prices were already languishing, and the Middle East was already in crisis. Osborne could have framed his spending review this way six weeks ago but chose not to, while he could have gone to Cardiff to make the familiar bullish defence of his economic strategy and chose not to do that either. Where’s the logic in all this?

The answer is Osborne’s highly pragmatic political approach. In November, the chancellor faced a double crisis in the shape of unpopular tax credit cuts and police budget reductions. Both had become unsustainable politically. So he emphasised the positive, increased his borrowing, magicked up some extra cash for tax credits and the police, and solved his problems. That mission was indeed accomplished.

This January there is a different political imperative. The imperative is now to win the EU referendum, provisionally slated for late June and now dominating everything else on the Conservative agenda. Today, as distinct from last November, it suits Osborne to emphasise insecurity, because that, he appears to calculate, is the best backdrop for winning the referendum argument and ensuring the continued British membership of the EU that he desires. The “creeping complacency” about the economy against which he warned in Cardiff would be the leave campaign’s best friend.

Given the party’s history and excitability on Europe, no senior Conservative of the Cameron-Osborne generation can risk going into the referendum making a full-hearted case for Europe of the sort Michael Heseltine or Kenneth Clarke might make – least of all a politician like Osborne, who wants the votes of the party to elect him to succeed Cameron. There will be no Blair-style talk of British destiny from the Tories in this referendum. Every pro-EU argument will be pragmatic and hard-headed to a fault.

And none will be more pragmatic and hard-headed than the argument about security that Osborne’s instinct tells him is central to winning the referendum. In the end, the Tory high command has calculated that a lot of currently undecided people will vote to remain in the EU because they think the country will be stronger within an alliance than by turning its back on Europe.

While this argument about security is partly about physical security in the face of jihadist terrorism, and partly also about the control of border security – where the mood in Europe is now much more receptive to British caution than it was a year ago – it is ultimately mostly about economic security.

If voters were confident that they would be more prosperous leaving the EU, the contest might be very hard to win. But an uncertain economic future makes the status quo much more attractive, as it did in Scotland in 2014 and, with the oil price where it is today, as it would probably do again in a second referendum on Scottish secession.

My hunch is that this most politically calculating of chancellors has reframed his view of the economy largely with the European referendum in mind. Labour’s abject lack of credibility on economic management – a poll this week shows only 18% of voters think Labour is the best party on the economy – provides the political space for Osborne to dare to paint a worrying picture about Britain’s vulnerability to the global economy that he would normally avoid. Call it Osborne’s Project Fear if you want. But if it helps win the Europe vote, then I shall be cheering him on.