Most British voters rejected conventional wisdom on the economy and party politics. Their Prime Minister will quit in October.

Their choice gives succour to anti-immigrant extremists worldwide and increases the risk of further European disunion.

The financial fallout in the short term was a record 10 per cent fall in the pound to its lowest levels in 30 years. Stock markets dived from London to Sydney.

With scant thought having been applied to the likely side effects of Brexit, global trade has been destabilised. No one knows whether the other 27 EU member states will punish or respect the British decision.

But we know many businesses will need to shift from Britain to mainland Europe to maintain operations.

Prime Minister Malcolm Turnbull has reassured Australians that "our very strong and intimate relations with the United Kingdom will be entirely unaffected"; likewise our links with Europe.

While it might take two years for Brexit to be completed, Australia will need to reshape its trade and financial relationships with both sides. 

As the Herald indicated this week, this is an economic setback. Britons have in effect voted for a doomed experiment to try to hold out against globalisation.

They have also taken the lure of returning to a cosy, monocultural past. 

Having destroyed the authority of the Remain leaders – Tory Prime Minister David Cameron, his Chancellor of the Exchequer George Osborne and Labour leader Jeremy Corbyn – the angry anti-immigrant core of Brexit will now claim legitimacy in British mainstream politics.

Eurosceptics across Europe are already seizing on the pro-Brexit majority in England to justify their own independents and push for tougher anti-immigration policies.

And strong votes to remain in Scotland and Northern Ireland raise the pressure for two more independence referendums that would allow them cut ties with England and stay in the EU.

The Brexit fallout will require careful management by both the EU and British sides.

Stability to soothe financial nerves is important. While Mr Cameron has been a strong negotiator and Mr Osborne has done well in Treasury, their ability to offer leadership on EU issues has been destroyed.

Mr Cameron has accepted that.

"I think the country requires fresh leadership," a teary Mr Cameron said last night.  

"I will do everything I can to deliver stability in  the next few months. I plan a period of stability and then the new leadership required … by the start of the Conservative Party conference in October. The negotiations with the EU will need to be undertaken by a new prime minister."

Brexit leader and former London Mayor Boris Johnson may well step up. Mr Johnson is volatile but a relative novice in Westminster and especially in strategic issues such as the relationship between the EU and the North Atlantic Treaty Organisation.

In addition, he would be leading a divided country. How Mr Johnson could bring the nation together when he has been so virulent in his pursuit of migration controls remains to be seen.

The Labour party under Mr Corbyn cannot expect fill the void. Traditional working-class Labour areas voted strongly to Leave.

More than ever Britain's politics looks divided between progressive, educated, globalised people in big cities and a disenchanted majority in the regions.

Into that vacuum will charge those aligned to the right-wing anti-immigrant United Kingdom Independence Party whose appeal under leader Nigel Farage forced Mr Cameron to hold this referendum despite his commitment to Europe.

But the lesson to all parties is clear: a majority of voters across the traditional political spectrum feel they are being ignored.

- Sydney Morning Herald