It is not just David Cameron’s admiration for the 1980s indie music of The Smiths that makes him want to conquer the north. If the Tory leader can close the north-south political divide that opened in that decade, it will be as significant a breakthrough for his party as New Labour’s southern gains in 1997.

Some Tory progress seems inevitable, even though Manchester, Liverpool and Newcastle, which have no Conservative MPs, remain resistant. Financial Times research showed recently that the Tories had built a four-point lead in the north, eradicating the 19-point Labour lead there at the 2005 general election.