With Britain as the mother country and the US as the alliance father, Australia has a dysfunctional family. Mum has gone nuts, Dad has gone rogue. The anchors of the Anglosphere are angry and adrift, distracted by nationalism mutating to nativism.

Forfeiting Britain's influence and power in the world? It has been a long week for British PM Boris Johnson. Getty Images

Domestically, the US system is so strong and dynamic it will recover from Trump. The worrying question is whether the international system that the US created can also rebound.

The prognosis for Britain is darker. The British polity is doing lasting damage to the nation. As The Financial Times chief economics commentator Martin Wolf observed in March, the UK "has fallen into the hands of lunatics engaged in an astonishing act of national self-harm".

I’ve always loved the Poms. I was fascinated by my grandmother’s stories of growing up in London, especially her memory of German zeppelins bombing the city during World War I. I’ve lived and worked in London (as an ABC correspondent from 1983-86, and our son was born there), but I’ve never doubted I was an outsider, branded on the tongue as foreign. So this is an outsider’s sorrowful view of what Brexit is doing to the Brits.

The 2016 referendum result was as much a vote against recession, austerity and the stresses of modern life as it was a vote against Europe. But visiting London last year it was clear the Brexit obsession had become permanent. And to be in London last week was to witness the lunacy gone amok.

Three big conclusions can be stated as established facts. First, British politics is deeply polarised. Another election is inevitable. The poll may deliver a realignment of political power, or merely entrench the polarisation. Second, Britain is leaving Europe. The economics of this is dumb, even mad. Britain will be relatively poorer because of Brexit. Third, Britain will be a weaker international power, with less diplomatic and strategic influence.

On the first point, it’s not too far-fetched to muse about Britain taking on some features of a failed state because of the way its politics and institutions are rupturing. Only this week, Scotland's High Court found Prime Minister Boris Johnson's move to prorogue Parliament was unlawful and that he may have misled the Queen about his true motivation – to "stymie" the democratic process.

Chris Patten, former minister and Conservative Party chairman, is one of those to summon up the failed state image, as British politics lurches to extremes on both the left and the right: "As Brexit looms ever closer, Britain’s institutions, economic prospects, constitution, and future are all at risk. But the reckless plunge into delusion and lies proceeds apace."

Those failed-state thoughts were penned before Boris Johnson moved to shut/porogue/sideline Parliament and then purged Tory grandees who voted against him.

On poorer Britain, the impacts are already being felt. Economic modelling shows the UK economy is 2.3 per cent smaller than it would be if Britain had voted to remain in the EU.

As the economics editor of The Times reported: "Confidence has fallen to its lowest ever level, consumer purchases have recently worsened, employment fell at one of the fastest rates in almost seven years and capital investment shrank ... Companies scaled back production in response to the steepest drop in new order intakes since 2012."

The Brexit assurance is that a tough transition will deliver a wonderful future. The reality is that Britain will impose permanent barriers on its biggest market.

Britain is going to transition to being poorer than it otherwise would have been. As the Oxford economist Simon Wren-Lewis keeps hammering: "What the UK is doing is utterly, utterly stupid. An act of self-harm with no point, no upside."

The third point about Britain being a weaker power, with less strategic and diplomatic influence, is where the lunacy really feeds on itself.

It’s tempting to say that in lurching towards the European exit, the Brits have chosen their history over their geography. In fact, Brexit is as ignorant about history as it is about geography and economics.

British diplomatic and strategic history is as Europe’s off-shore balancer. That strategy means being deeply involved in Europe to preserve the balance, not sulking off-shore.

David Blagden, from the Strategy and Security Institute at the University of Exeter, notes that "after nearly 500 years of seeking to prevent a single great power from controlling the whole of western Europe, British withdrawal from the European Union could pave the way for precisely that outcome".

Johnson, the man who loves Churchillian World War II images, is going to surrender to the Germans. Winston Churchill would be equally astonished at his nation cutting loose from France and leaving Russia to do its worst.

Exiting the European superstate means giving up Britain’s historic role. This is turning away from traditional balance-of-power realism as well as abandoning the great European effort to live in peace.

Martin Wolf commented in July: "The UK the world thought it knew – stable, pragmatic, respected – is gone, probably forever. Lost reputations are not easily regained." Whatever Britain emerges from the other side of Brexit, it will have a reduced role and reputation in Europe.

Britain is going to have less say in what Europe does and how Europe acts. Less diplomatic influence. Less power. Britain’s oft-cited "special relationship" with the US will be less special and less important. A poorer nation with a fainter voice in Europe will have a weaker voice in Washington.

Polarised, poorer and with less power – Britain is bereft by Brexit.

Graeme Dobell is a journalist and a fellow of the Australian Strategic Policy Institute. This article first appeared in APSI’s publication, The Strategist.