Scotland can, should and hopefully will leave the United Kingdom. The question for non-Scottish Brits now is, if we are going to say goodbye to the union, how should we frame our own national consciousness after that? What institutions should we design?

The original argument for independence was strong: Scotland has developed a national culture and consciousness on a different trajectory to that of England. Large numbers of its people are convinced their economic interest is harmed within the current structure of devolution. With a hard Brexit, all forms of devolution seem an inadequate protection from the bomb that is about to go off.

Theresa May’s determination to pursue hard Brexit is the equivalent of stepping off a 10-metre diving board without checking there is any water in the pool below. But a no-deal Brexit will not only trigger severe economic dislocation. It will trigger an ideological crisis of all the nationalisms in the UK. English nationalism – half-formed, turbulent and untheorised at the moment it defeated Ed Miliband and then delivered Brexit – will be forced to become concrete. Leaping off the diving board handcuffed to May will be bad enough; leaping handcuffed to a people having a national identity meltdown is definitely something to avoid.

I wrote on the morning after Miliband lost the election, that “I don’t want to be English”. The past 20 months have only strengthened that view.

It is impossible to become passionate about a nationalism that did not exist when you were at school; whose key symbols have had to be cleansed and re-cleansed of association with xenophobia and racism, and which – above all – had no basis in economic reality until last year. My passport says I am British. Thirty years of globalisation, travel and education have left me – unapologetically – one of those “citizens of nowhere” derided by May.

At school, we were taught about the British empire, its crimes and victories. I learned that, at Waterloo, the Gordon Highlanders clung to the stirrups of the Scots Greys as they charged. Nobody told me that image would one day have to become something “other” to my own national identity. Ditto for the image of King’s Own Scottish Borderers dug in at Arnhem.

English literature meant learning not only the poems of Robert Burns alongside Keats but also those of the Irishmen, Yeats and Wilde. Sure, there probably exists a form of Anglo-Saxon English, uninflected by the lilt of Celtic or the syntax of people from Britain’s former colonies. But I don’t know anybody who speaks it.

However, English national consciousness is becoming a logical response to the way the world is changing. Even if, as Gordon Brown proposed at the weekend, Scotland accepts a federal settlement – the Bank of England becoming the central bank of an effective sterling union, etc – England must be given its own democratic institutions.

But if Scotland leaves – and Northern Ireland is given some kind of halfway status to prevent a border being re-erected with the Republic – then what’s left cannot be called “rUK” – the rump or remainder UK. It will be England-Plus. This new country will still be a major global economy, a nuclear power (albeit in need of a new port for its nuclear-armed submarines), a permanent member of the UN Security Council and home to the head of the Commonwealth. And it will need an ideology.

But here is where the problem begins. Just as it’s hard to deglobalise a national economy, breaking up an imperialist ideology into its constituent parts is going to be very tricky. The British imperial ideology, and its post-imperial successor after 1945 was the creation of a national bourgeoisie. Wellington’s reported comment about Waterloo being won on the playing fields of Eton was not fatuous: the creation of an elite with a common approach for conquering and dividing other countries, and ruling its own, required a common set of economic practices.

The modern English elite is scarcely a national bourgeoisie at all. It is, at best, a multi-ethnic community of innovators and financiers who happen to live here, heavily intermarried with old English – and Scottish – money. Watch a rugby match at a top British private school and you will understand how anachronistic Wellington’s comment would seem today.

However, if Nicola Sturgeon leads Scotland to independence by 2020, establishing something close to the Scandinavian model of capitalism on British soil, the English elite will have to come up with a new story.

You can see it forming now, in the pages of the rightwing magazines and websites feeding off the corpse of liberal conservatism. Scotland’s desire for independence is being cast no longer as simply unwise (as in 2014) but unjust. It is being subtly reframed by the English right as a form of theft, disloyalty, disobedience and disruption, a wilful sabotage of the Brexit process.

If the left and centre of English politics do not resist this – and consciously offer something different – this anti-Scottish resentment story will become the core of the new English ideology. It already has, as Patrick Cockburn pointed out in the Independent, something in common with the resurgent European nationalisms: ethnic and cultural exclusivity.

So what can we do? Some figures on the left have argued for an English parliament. I dismissed this proposal two years ago, but Brexit has convinced me the federal argument is strong.

That raises the question: what form should English federal institutions take? Given the opportunity to redesign the English political institutions along federal lines, we should push not for an English assembly, but for powerful regional states, along the lines of the German länder. The result might look a lot like the map of the British isles around 830 AD, once Wessex was a unified kingdom – with the equivalents of Mercia, Northumbria and Wales each having a devolved assembly.

Here is why I favour that solution over a single English parliament: in any English parliament, the south-east will dominate; and the emergent ideology of an English nation state will form itself around the white, military-monarchic and financial elite. With the Scots gone, their replacements as the social laboratory for far-right economics will be the north and the Midlands of England. If we are really unlucky, and Ukip does not evaporate, the racial and religious exclusivity ideologies will get stronger.

Better to create a strong federal institution at the centre – and offer Scotland and the Republic of Ireland strong bilateral arrangements over, for example, defence and trade – and then create strong regional assemblies. That is the best way of representing the separate regional identities of the English, and of allowing Wales to participate as an equal to the other regions, rather than as an appendage to Great England.