London.

Australians are well known as admirers of the Ealing comedy, and no art form has ever been invented that would do more justice to the current debate about whether Scotland should separate from England. With a little over three months to go before the plebiscite on 18 September a discussion marked by deceit and incompetence on both sides ought to have left the electorate in deep confusion about what to do for the best. But then the debate only reflects the tone of argument in years of squabbling, claim and counter-claim that led up to the people of Scotland being offered a vote in the first place, and pays little attention to the fact that the fourth or fifth (depending upon which data one reads) most significant country on the planet could be about to break up.

New readers should start here. Scotland and England have shared a monarchy since 1603, when Elizabeth I managed to die without issue and the crown worn by the House of Tudor passed to her kinsman, James Stuart the VIth of Scotland, who became James I of England. A political union was forged in 1707, with the Scottish parliament in Edinburgh brought to an end, largely because an imperial expedition to Darien (what is now Panama) in the 1690s ended in disaster and with Scottish finances badly damaged. The question of English money supplementing Scottish bawbees has been prevalent, and increasingly toxic, ever since.

In the 18th and 19th centuries the Scots largely built the British Empire. They more or less invented Canada. They colonised large stretches of Africa, which is why to this day if one attends ceremonials in certain southern African capitals, one will hear and see black men perfectly attired in tartan playing the bagpipes. They played an enormous part in running India, were prominent in New Zealand and their descendants are even believed to be living among those of the English, Welsh and Irish in Australia. The British Empire was the perfect project to bind Scotland and England together in a common cause. Scottish regiments suffered disproportionately higher casualties than English ones in the Great War, making it all the more ironic that this centenary year of the conflict may yet include the event of Scotland becoming independent. And Scotland made a distinctive contribution to the arts and sciences — Burns, Scott, the Carlyles, Buchan and Conan Doyle for starters, not to mention Alexander Graham Bell inventing the telephone, John Logie Baird inventing television and Alexander Fleming inventing penicillin. Add to that Scotland’s gift to the world of whisky, and one should be in no doubt that we are dealing with a formidable people.

Once the project of empire was over, however, something changed. There had always been a latent suspicion of the Englishman and his motives, and one Englishman in particular — Margaret Thatcher — seemed to have been put on the earth to torment the Scots as a post-biblical version of whips and scorpions. Two modern English inventions of which the Scots became unduly fond were trade unionism and welfarism. A lethal cocktail of the two undermined Scottish industry and morale between the 1960s and the 1990s. Long before Mrs Thatcher entered Downing Street in 1979 industrial Scotland was a proverbial hotbed of militancy — Glasgow’s former shipbuilding district was not called Red Clydeside for nothing — and urban Scotland, hitherto distinguished by an enviable work ethic and sense of aspiration, was becoming addicted to welfare. In a philosophical shift unthinkable to their grandparents, Scots embraced the something for nothing society. On the rare occasions things went well they congratulated themselves; when things went badly they blamed the English.

Throughout Mrs Thatcher’s 11 years in power the fortunes of the Conservatives sank in Scotland: today, the party that won nearly a third of the parliamentary seats at the 1979 election barely exists there. The biggest nail in the coffin was deemed to be the community charge or poll tax, the system of local government financing introduced on an experimental basis in Scotland in 1989 before being implemented in the rest of the United Kingdom the following year. The Scots still nurse this grievance with ferocity today, claiming it is because they were singled out for early implementation. In fact, they objected to the principle of the poll tax — that every adult on the electoral register should make a contribution to local government finance — because many of them felt that paying taxes ought to be the responsibility of someone else. They were in good company: millions in England and Wales felt the same. The poll tax lasted only a couple of years and was partly responsible for Mrs Thatcher’s downfall. But whereas everybody else in the kingdom moved on, the wound still festers in Scotland, and the matter was virulently exploited by the Labour party and, more potently still, by the Scottish nationalists.

The parliament at Westminster had debated Scottish devolution in the late 1970s, but a referendum in Scotland in 1979 had rejected the idea. The Labour party put the matter back on the agenda in the mid-1990s, promising a further referendum should they be elected to power nationally. Four months after Tony Blair won in 1997 the vote happened, and Scotland voted for what we used to call Home Rule — a parliament in Edinburgh taking control of domestic policies, while matters such as foreign affairs, defence and the national lottery (sic) were left in Westminster’s hands. The parliament convened in 1999.

Labour’s enthusiasm for Home Rule was entirely cynical. At a time when a third of the British cabinet was comprised of Scots (including at one stage the Prime Minister, Chancellor of the Exchequer, Foreign Secretary and Lord Chancellor) Labour was also confident it could control Scotland: and it did, winning the first elections there and governing in a coalition with the Liberal Democrats. Apparently convinced they were establishing a 1,000-year Reich both regionally and nationally, Labour ministers of Scottish origin — notably the deeply flawed Gordon Brown, who subsequently became one of the worst Prime Ministers in British history — spoke frequently of devolution making the United Kingdom ‘stronger’. A few of us realised the opposite was true: devolution would provide a platform for Scottish nationalism, which the nationalists would soon seize and control, and when they did they would offer a vote on separatism, which the Scots might well elect to have. This is not post-facto wisdom, by the way: in 1999 I published a whole book outlining this process and predicting it would happen.

The Labour party in particular has watched with mounting horror the ineptitude of the so-called “Better Together” campaign, run largely by Scottish Labour grandees (the figurehead has been Alistair Darling, the last Labour Chancellor of the Exchequer, though he has been rather sidelined of late) because any Tory or Liberal was deemed too toxic. Labour’s old arrogance has permeated the campaign, leaving many Scots feeling that such people, cosy in the well-paid and internationally recognised world of Westminster politics, simply do not understand them and take them and their votes for granted. The opinion polls, in which those who wished to keep the status quo began well ahead, have narrowed, though the narrowing has stopped in the last three or four weeks, creating the suspicion that everyone who might be tempted to vote for separation has now been reached. It is difficult to find anyone in England who imagines the Scots will vote to leave the United Kingdom, because the English believe (with some justification) that they subsidise the Scots, and turkeys do not vote for Christmas. They may be right: but anything is possible.

The Ealing-comedy nature of the campaign has been not least because of the apparent unavailability of reliable data. The Scottish National party claims, using data that is widely regarded in the City of London as being about as reliable as Argentina’s, that it contributes more to the United Kingdom than it takes out. Nobody south of Gretna Green believes this, and the truth would rapidly become apparent if Scotland votes to secede. Yet the Treasury has not helped matters by not releasing up-to-date figures. The last generally available are from 2009-10, which showed Scotland receiving £63 billion in public spending and contributing £48 billion in revenue. Scotland’s two main banks, RBS and HBOS, were once hailed by Alex Salmond, the charismatic leader of the SNP and Scotland’s First Minister, as the engine room of a Scottish financial industry that, together with North Sea oil, would power the nation into independence. They are now largely owned by the taxpayer following their near-collapses in the crisis of 2008, and having a job getting out of first gear. As for Mr Salmond’s fantasies about oil revenues: stocks are dwindling, fracking is driving down the price, when territorial waters are drawn up he may find some of what he thinks is his oil in the North Sea will actually be England’s, and the Shetland Islands — in whose waters much of his reserves lie — say that if Scotland goes independent, they will seek to re-join Norway. That is an Ealing film all on its own.

A Tory MP told me the other day that one reason — he thinks — why the government has not released better data about the Anglo-Scottish economic relationship is that the true figures are so bad for Scotland, and so destructive of the SNP’s line that they would be better off financially on their own, that to release them would be viewed by many Scots as an act of sabotage that would drive thousands more, in anger, into the arms of the Nationalists. That may or may not be the case. Certainly, when other hard facts have been pointed out to the Scots in recent months that would give most sane people pause for thought, they have merely succeeded into goading more Scots to consider a vote for separatism. So it was when the President of the European Commission told Scotland that to separate from England would mean it having to reapply for membership of the European Union, which could take several years and be contingent on a promise to join the austerity-ridden eurozone. And so it was when George Osborne, the Chancellor of the Exchequer, said that England had no intention of forming a currency union with an independent Scotland — and quite right too, given the awesome liabilities and lack of control this could impose on the English taxpayer.

If the vote is for separatism on 18 September, there will be chaos on both sides of the border, because neither divorcing party understands the consequences. Between them they must split national assets and, more to the point, the national debt, and that will be especially ugly. But what about the Armed Forces? Will there be border controls? What happens to the millions of Scots in England who consider themselves Scottish? And what about the 40 or so Labour MPs who might be elected in the British general election next May for Scottish seats, enabling Labour to form a government, but who would be evicted from Westminster on 24 March 2016, independence day? Some are calling for the British general election to be postponed until 2016 in the event of a vote for independence, and they have a point.

But the real problem would be for the Scots, suddenly told to put their lack of money where their mouth is. A capital flight of billions of pounds is predicted should they vote for independence, and many businesses have made contingency plans to go offshore or to relocate. There will be no currency union. Scotland will find it harder, and far more expensive, to borrow money. This is not a process that will be completed with a simple handshake and a cry of ‘fare ye well’.

But that is just one of the many truths that few can bear to tell in this surreal summer of campaign, and just one of the many profound shocks that awaits this proud and once enterprising people if they elect to go it alone.