The clash of metropolitan London with course Ulster is stark and ancient.
Ulster's loyal citizens have variously been described as the "despised tribe", the "despised hangers-on" and the "politically damned".
Gladstone said the Irish question was a curse on Westminster.
Churchill spoke of Ulster's dreary steeples.
Everyone from Reginald Maudling to Jeremy Paxman, to an HBO executive have cast the north of Ireland in a nightmarish light.
Until Gerry Fitt challenged and ended the constitutional convention of non-interference in Northern Ireand affairs, Westminster was almost totally silent and blind to the Irish pene-exclave. As Paul Rose said in the Commons in April 1969:
"We also faced the convention of non-interference, a convention which in that debate prompted my hon. Friend the Member for Thurrock (Mr Delargy) to ask you, Mr. Speaker, what, apart from Short Brothers and Harland and Wolff, we could mention in a debate on Northern Ireland. That convention is dead. It was killed when my hon. Friend the Member for Belfast, West (Mr Fitt) was seen by millions of television viewers, his head streaming with blood after a vicious batoning while surrounded by a group of members of the Royal Ulster Constabulary."
Newton Emerson explained that had been part of the wider attempt to decouple defiant Ulster from Britain in the years after Ireland's partition:
"From the creation of Northern Ireland in 1921, devolution was intended to make everyone feel less British and ultimately to ease us out of the United Kingdom altogether."
Ignored from 1922, Northern Ireland was forced onto the tables of Whitehall by 1969.
But from then to now, from the period of Direct Rule to the current devolution settlement, effete London has done its best to avoid brutish Belfast.
Mainland society has en masse blocked their Irish countryfolk from their consciousness.
Of course the revulsion and ignorance of Northern Ireland is not total, Ulster's British six-counties would still be mired in the bog of reprisals were it not for Major and Blair and their legions of refined bureaucrats.
But it remains that the less heard of and from obstreperous Ulstermen in the halls and clubs of London, the wonderfully better.
And this was especially so for David Cameron. Sam McBride of the Belfast News Letter wrote a comprehensive overview of Cameron's legacy in Northern Ireland.
McBride makes a number of points. Cameron broke with NIO convention, ignoring two major norms.
He apologised unreservedly for Bloody Sunday, an event that is very difficult for Protestants to respond to, as I've written here.
Before delivering his speech in the Commons the Prime Minister had the option of delivering an initial draft speech which was soft and equivocal. In June 2010 only a month after taking to Number 10 he opted to revise it and to extend a clear and unequivocal hand of apology.
Only a few months later he defied another convention. Breaking a habit set by Blair and Brown, the DUP-Sinn Fein duopoly would not be molly-coddled, rather Cameron would play the stern, cold and distance school master.
Any communication was made through official conduits, first Owen Patterson then the recently departed Theresa Villiers. As Sam McBride wrote:
"If [David Cameron] wanted to deal with Northern Ireland matters on a day to day basis, he would have appointed himself to be Northern Ireland Secretary."
Cameron stuck with his new protocol in spite of Ulster consternation, including the frustration of the NIO. McBride sees Cameron's legacy in Northern Ireland, whether by design or chance, as a positive one:
"When it came to Northern Ireland - so often an adjunct to British politics - David Cameron might not have been an expert, but he knew his own mind. One source says that although he believed in staying out of the fine detail, "when need be, he'd be very decisive with his interventions in Northern Ireland".
That confidence that Stormont was far more stable than its leaders claimed led him to repeatedly face down the Executive, and particularly Sinn Fein over its threats about not implementing welfare reform.
Although Mr Cameron did not prove entirely doctrinaire during the dispute with nationalists on welfare reform, and allowed Stormont some flexibility on how the changes operate in Northern Ireland, he was resolute on the core of the dispute: there would be no additional money for welfare in Northern Ireland.
Having been the first putative Prime Minister to campaign in Northern Ireland for more than three decades after re-establishing the Conservative Party's link with the Ulster Unionists, Mr Cameron came into office with more direct understanding of the Province - even if it was with a clear unionist bias - than many of his predecessors. If Stormont had fallen apart on his watch, his confidence would have seemed like detached recklessness, but through luck or judgement the various political crises in Belfast ended with minimal input from Downing Street. His approach was so low key that even in major negotiations such as those leading last year's Fresh Start deal the participants speak of the Prime Minister leaving much of the work to his secretary of state and the NIO.
Despite Mr Cameron left office with Stormont far more stable than when he was elected in 2010 (and he cannot take more than a small part of the credit for that), many people on this side of the Irish Sea still struggle to see his approach as being founded on anything other than indifference.
And yet even if that simplistic interpretation is correct, it is unquestionably the case that the DUP and Sinn Fein are far closer together today than was the case six years ago.One DUP figure familiar with that period says of Mr Cameron's arm's-length approach to Stormont that "we didn't mind that - the difficulty was Sinn Fein getting their heads round that"."
The News Letter political correspondent concluded:
"Even before Brexit came to define David Cameron's legacy, Northern Ireland would have occupied just a few pages in his biography. But - with less energy but as much determination as Tony Blair - Mr Cameron has left a distinctive mark on Stormont, and on Northern Ireland."
Inversely, as Newton Emerson wrote Sinn Fein have at times, such as around the Welfare Reform crisis, wanted the "Brits In".
Newton Emerson was overflowing with praise for Cameron's handling of his Northern Ireland envoy Theresa Villiers. In one article from November 2015 Newton Emerson wrote:
"It is time to pay tribute to our glorious leader. Secretary of state Theresa Villiers has spent almost two years chairing all-party talks and adjudicating related 'crises'.
Throughout that time she has sent a signal of studied indifference, verging at critical junctures on ambivalence, while David Cameron has continued referring everything through her...
In the end, nobody out-brinked the Ice Queen of Hillsborough Castle."
In another article from April 2016 Newton Emerson wrote:
"From 2012-2015] it became apparent London was disengaging as an active, positive policy, to force an indigenous deal it felt would be more likely to stick. Northern Secretary Theresa Villiers was specific about this, in word and patient non-deed, while David Cameron referred all demands for "crisis summits" back to a blasé Villiers. At the same time, Stormont parties had top-level access to British treasury and welfare ministers whenever they wanted to discuss practical solutions.
People in Northern Ireland began to enjoy the strangulated spectacle of their elected representatives realising they would have to sort out their own arguments. Some people even began to believe it might work, or at least that it was the only thing that ever had a chance of working."
Cameron's studied indifference and the return of London non-interference has mended and made the Stormont marriage stable, albeit loveless. Maybe Cameron's legacy isn't a total mess.
Yet again, the Brexit mess Cameron has left Britain and Ireland with could yet prove to be one of Ireland's greatest challenges.
[Fair fa ye'* means Farewell in Ulster-Scots]