British Prime Minister David Cameron speaks to supporters during the launch of the Welsh Conservative manifesto on April 17, 2015 in Builth Wells, Wales. The Prime Minister is spending the day campaigning in the West Midlands and Wales. AFP PHOTO / POOL / Peter Macdiarmid Image Credit: AFP

It is not often that you see Poles drunk and disorderly in the afternoon, but I had the dubious honour on the London Underground last week. As he sat, drinking and cursing, the Brits looked at the floor quietly, pretending that nothing was happening. But the foreigners were outraged. A young Russian woman confronted him. “Right now, immigrants are not very popular here,” she said. “It makes me sick when people like you cause what’s happening.”

Another Pole at the end of the carriage then piped up, telling the drunk that there were children present and that he was a disgrace. He staggered off at the next stop. The Russian was not quite right. Immigrants are not so unpopular in London — it would be a form of self-hatred: A third of the city’s residents were born overseas, making it as great a melting pot as New York. Half of London’s children have immigrant mothers.

With booming wealth and diversity, London is now its own capital — a glittering citadel that has never had less in common with the rest of the country. Which makes it a rather bad place from which to govern. Yet again, during the election campaign, we see the farce of London’s political class chasing each other around the country and pretending to engage with ordinary voters. But all are careful not to come too close to any real ones.

Prime Minister David Cameron held one rally in the corner of an empty cowshed, in front of activists assembled for the camera. On his trip to Manchester, Ed Miliband recently made sure that the train doors were kept closed as he disembarked so he could clear the platform in peace. Last week, the Liberal Democrats’ battle bus broke down a mile away from Westminster, as if terrified of the impending journey. Miliband need not spend a day of the campaign in London: The city is already his. The agenda he has put together over the past five years seems to chime perfectly with the values of the capital.

Labour may be neck-and-neck with the Tories in the United Kingdom as a whole, but a ComRes poll of Londoners gives Miliband an astonishing 14-point lead. His party is even ahead in Margaret Thatcher’s old seat of Finchley. If the values of the capital resonated with the values of the West Midlands, then Miliband would be home and dry. If London were its own country, it would be the richest in the world. The average property now costs £500,000 (Dh2.74 million), twice the UK average. It also has the most highly educated workforce: 60 per cent of London’s workers are graduates — again, twice the level of the North. Disposable income in west London is now three times the level of Leicester or Nottingham.

And while the city has its problems, failing state schools is not really among them — school reform has been centred in the capital, with great effect. Outside the M25, there has not been so much to boast about. Support for immigration is the point where London and the rest of the country most differ. Labour’s education spokesman, Tristram Hunt, visited a primary school in Derbyshire yesterday and asked an angelic-looking child whom he would vote for. “Ukip” (United Kingdom Independence Party) , the reply came. “I’d like to get all the foreigners out.”

Such a response would be unlikely in London, where half of primary school pupils have foreign-born mothers. In the capital, just over half say immigration is good for the economy — for the rest of the UK, it is just over a quarter. So it is easy to see why Nigel Farage has had fun suggesting that the UK’s policy on immigration, which troubles voters the most, has been made in London by London. When he denounces “metropolitan” values, this is what he means: a latte-sipping London which cannot begin to understand the problems facing those outside it. A city whose priorities (environmentalism) are just not shared nationally. He portrays Ukip as the only real choice in an election where the choice at the election is not Right vs Left, but Notting Hill vs Primrose Hill.

This problem is more complex than the north vs south divide: Ukip’s only electoral prospects lie in the south, but it leaves Londoners cold. And Farage is far from alone in being rude about the capital — the Scottish National Party (SNP) frequently denounced “London rule”. Even Jim Murphy, the leader of the Scottish Labour Party, has positioned himself as a Robin Hood out to lighten Londoners’ pockets. He has promised Scotland 1,000 new nurses and boasts that this would be paid for with a mansion tax aimed at wealthy Londoners.

The SNP wants separation, runs his argument, but only Labour can hurt Londoners! He has a point, in that the capital’s vast wealth does feed the growing concern about inequality. The economic output of London’s financial Square Mile is now greater than that of Glasgow and Edinburgh combined. But the beauty of the Union is that it does pool resources, and that the capital (and its opportunities) is a resource to be enjoyed by all. When I visited my old school in the Scottish Highlands recently, pupils spoke about wanting to work in London — and as citizens, not as immigrants. This has always been the case.

To hear London denounced in the same way that some Americans talk about Washington is a new, and deeply unwelcome, feature of British national debate. But the very idea of national debate is fading. Neither main party is likely to win a majority next month because neither is truly appealing to the whole nation: Each is focusing on a list of target voters, in swing seats.

The only party truly speaking to a whole country is the SNP, with stunning results. Next month, Britain risks becoming a tripartite country where the nationalists rule the north, the Tories dominate the south (cities excepted) and Labour takes the middle. Even some of those Cameron appointed to his Cabinet fear that the Tories are in such trouble now because the “modernisation” project was too heavily influenced by metropolitan (that is to say, London) values.

And that Ukip only exists because the Tory leadership gave up on such voters in the same way that it gave up on Scotland. The prime minister is fully aware of such concerns and how they feed into the wider concerns about a remote political class. This is why he will spend almost every day between now and May 7 outside of London (his record is 26 visits in one day).

And this also explains George Osborne’s near-obsession with creating a “northern powerhouse” by doing what he can for the economies of the north. When the Speaker, John Bercow, recently declared that the House of Commons was crumbling and may have to be abandoned, this raised an intriguing prospect: should Parliament move to Manchester, or York? But there is a more pressing problem: the absence of a genuinely national party, able to appeal to the inner cities as well as the shires; able to win seats in Dundee as well as Dunstable. Bercow said that the Palace of Westminster may only last for another 20 years. It’s unclear if the same can still be said about the United Kingdom.

— The Telegraph Group Limited, London, 2015