The choice facing the Labour Party in this leadership election is not between principle and electability. This image of the contest is essentially wrong. The party does not face a choice between the pursuit of electoral success through political pragmatism and leadership under Jeremy Corbyn, whose principles will land the party on the electoral rocks. The alternative pragmatism spells electoral failure too, even if in a less spectacular form. History will see this leadership contest marking the end of Blairism.

This is the reason why the Labour establishment is finding it so hard to come to terms with the support Corbyn has gathered. The party is now in unchartered territory in which the map that has guided Labour politics since the early Nineties shows no clear direction for the party to follow.

Corbyn’s surge of support challenges what would have been a natural succession of power within the Labour Party. Yet however much Yvette Cooper, Andy Burnham and Liz Kendall claim to be rightful heirs, their kind of Blairism appears to a growing number of Labour members as thin political gruel.

That leaves Corbyn storming ahead. But his political ideas have really been too little challenged. It seems accepted even by his supporters that they could not form the basis of an effective opposition, let alone a programme for government.

There are, of course, aspects of his policies which raise activists’ spirits: the abolition of Trident; his emphasis on youth employment. His message on the need to build homes overwhelms any caution people might feel about his demand for rent controls.

It is the dearth of political ideas on the part of the other candidates that has allowed Corbyn to command the soft Left of the party — where its heart has always been. One only has to read the findings of Jon Cruddas’s research on the movement of voters away from Labour at the election to realise that Corbyn will be leading Labour into a political cul-de-sac. His analysis presents voters as polarising into three broad, sometimes overlapping, groups. The first, about a third of the electorate and the largest among party members, are socially liberal, altruistic, at home with the modernity of city life, better off than most voters.

The priority of the second group, 37 per cent of voters, is to improve their income and social status. The third group is socially conservative with values centring around the home, the family and national security. They tend to be found among older voters and make up 29 per cent.

Labour in the election witnessed a collapse in its support among its previous bedrock vote in this third, traditionalist group. Some 24 per cent of the Ukip vote came from Labour’s social conservatives.

These voters are more likely than others to mention immigration, toughness on welfare, Europe, national security and fiscal responsibility as important. Any Labour recovery must be based on developing policies that win them back in a way that also appeals to other groups.

How might that be done? To begin spelling out that challenge suggests the impossibility Corbyn would have in leading the party to victory. George Osborne’s living wage initiative holds the promise of laying the foundations of a new welfare consensus, with a decisive turn against means testing. But can Corbyn support the policies to make this strategy a success? A living wage would be a disaster unless it becomes integral to a wider strategy of raising productivity.

But how do we do that in low-paying industries when we have open borders with the EU supplying endless numbers of workers keen to work, so that raising skill levels at home is a non-starter? Yet raising productivity in low-paying industries could start a wider transformative industrial policy. How can we do this if we continue the policy of open borders? Corbyn is never going to renounce this aspect of Blairism, dressed up as internationalism. But this is the beginning of post-Blairism.

Likewise with welfare. Our core working-class vote deeply resents our “open borders”-type welfare state. We run a National Health Service and a national welfare policy. The operative word here is “national”. Yet Labour is all too often found to be sounding as if it supports a health service and welfare state open to all-comers, as if it should be part of our enormous international aid budget. Who is going to begin the development of post-Blairism by arguing for a welfare state based on past contributions so welfare entitlements begin to define our borders?

Likewise with housing. The green belt has served developers and current owners all too well. It’s one reason why the cost of land has risen from 25 per cent to 50 per cent of the total cost of an average home. We must tackle the inviolability of the green belt if this is to change. But what is the point of building more houses if our borders are open and no one knows how many people will be seeking accommodation in 2020?

Likewise, if we believe the main basis of welfare is contributory, shouldn’t long-standing citizens be at the front of the queue for social housing and other areas of welfare? Corbyn again rejects an approach that holds out the possibility of building a wider coalition of voters prepared to give voice to the poor.

The polls show that a new coalition of voters is willing to sign up to this kind of programme on health, welfare, housing and immigration. They have already moved into post-Blair Britain. But all the leadership candidates are, like Lot’s wife, frozen, staring into the past.

Yet it is with post-Blair politics that Labour can begin to forge a coalition of voters whose sharp elbows will advance not only their own interests but those of the weakest. Here are the beginnings of a route back to power. But who will lead us? Will these potential voters have to wait for a leader to emerge only after the razzmatazz of this current contest is forgotten?