Jeremy Corbyn is 66. By the time of the next election,  he will be almost 71. The time of the one after that, almost 76.

His refusal yesterday to confirm that he will lead Labour into the 2020 contest was thus a recognition of the obvious. He entered the party’s leadership contest to fly the flag for its hard left, not expecting for a moment to win it‎. It may be that he is rejuvenated by his triumph, and goes on to square up to George Osborne (or whoever the next Conservative leader turns out to be) in 2020.

But the most likely turn of events is that he works to consolidate his landslide win and impose his mandate on the whole party – on Labour’s policy, constitution, culture and personnel – before handing over to a new leader from the Party’s left, perhaps Angela Eagle or Lisa Nandy. A woman Labour leader is badly overdue. At yesterday’s announcement, every a single speaker was a man.

Much ink will be – and already has been – spilt over how left-wing Corbyn is. But a list of duties he will have to undertake as Leader of the Opposition makes the point ‎almost as well as a list of policies.

He will need to turn up at the Cenotaph on Remembrance Sunday. (Donkey jacket, anyone?) He will be expected to visit our armed forces abroad. He will have to drop in on an agricultural show – if Labour even pretends to take the countryside seriously – where his experience of having an allotment may ease the conversation, but which he will find almost as awkward as his hosts. This holder of a free bus pass will have to use an official car. He will be obliged to do PMQs. His trip to Northern Ireland will go down a storm with the Unionists – that’s at least two potential coalition partners for Labour ruled out already. He cannot avoid responding to the Budget. He will travel to meet the President of the United States of America – a country whose leaders he has consistently slagged off. More to the point, he will have to meet the Queen.

It may well be that Corbyn seeks to avoid doing some if not most of these things: we read already that he wants to duck facing David Cameron each week at the despatch box.‎ But such evasive action will only serve to draw even more attention to his weaknesses and unsuitability than turning up would have done. Almost anyone else would look more convincing as Leader of the Opposition. And we can trust in Tom Watson, who today is the man really in charge of Labour, to ensure that almost anyone else, including perhaps himself, duly does.

This explains why Cameron and Osborne are already striving, as Henry Hill explained yesterday on this site, to tar Labour semi-permanently with the Corbyn brush ‎- to discredit them for a generation. They want to frame the debate for the 2020 poll, whoever leads Labour into it, and do to the party over the next five years what Margaret Thatcher did to it during her first four: that’s to say, lock in its trashing of its own reputation, and turn a modest majority into a landslide.

The Thatcher era saw the Conservatives take defectors from Labour, such as Reg Prentice. Chuka Umanna, Tristram Hunt and others are already turning away from Corbyn. The Chancellor will already be mulling how to make disillusioned social democrats turn from Labour ‎to the Tories – just possibly these people, far more likely others. But Osborne is a political child not of the Thatcher era but the Blair one, and the defector he is more likely to mull went the other way. It was Sean Woodward, Cameron’s own predecessor in Witney, who later said that anyone could be a member of New Labour “regardless of class or view”.

The Conservative leadership will seek to rush change through while Labour is in disarray: as we know, it is weighing whether or not take students out of the immigration figures. It will try, too, to split Labour in the Commons: as we saw earlier this week, it is warming up for a new vote on ‎military action in Syria. But the most important strategic decision it has to take is whether or not to turn the Party into one which anyone can join and support “regardless of class or view” – in other words, make the Conservative Party the modern equivalent of Stanley Baldwin’s National Government. Cameron and Osborne have already chewed and spat out the Liberal Democrats. Now they have a chance, as they see it, to gobble and swallow New Labour, its voters and their successors.

There is electoral strength in being a party that looks and sounds moderate, that occupies a great swathe of political ground, and that becomes the natural one of government: “I don’t have any politics – I vote Conservative.” But a question that follows for Osborne and Cameron is less about how they hold power but what they do with it. How will they use the Party’s fledgling One Nation dominance?

As Mark Wallace intimated on ConservativeHome yesterday, they could make their leitmotif of “Security” the successor of Baldwin’s “Safety First”, snooze on their oars, and let the tide sweep them towards 2020. Or they could speed the radicalism that Ian Duncan Smith, Michael Gove and Theresa May displayed during the Coalition years – reducing worklessness, bringing in more academies and free schools, reforming the police. Young people need homes. The long-term unemployed, many of them younger men with poor education, rely on the benefit system. Reliance on quantitative easing has made saving very difficult. On homes, jobs, savings – the themes of the ConservativeHome Manifesto – and so much else there is so much to be done, not least by way of ensuring intergenerational and social justice. Corbyn is not a test of what Labour is made of – since we know the answer now – but of what the Conservatives are made of.