THE drama of Labour and Tory defections has forced British recognition of their own 'tribalism', supposedly Brexit-born.
Last week's group walkouts, a rare exercise, brought reflection about the upheaval of such moves.
One of the sanest thinkers wrote that leaving parties, switching parties were "enormous decisions" which meant "ruination of friendships and the wrecking of family relationships".
Having always mocked the 'sectarian tribalism' of our 'abnormal' politics, thinkers in Britain now despair at the revealed 'sectarianising' of their own system.
Others see possible progress: might proportional representation be mustering at last over the hill?
Those who jump ship here have never found life easy but at least among the young and energetic action of any kind can keep despair at bay, good in itself.
'Stop Climate Change. Fight for System Change'. So posters on Belfast lamp-posts advertised a meeting last Friday night in Queen's Student Union, urging membership of 'Socialist Youth NI. Support the school strikes. Build a mass movement to put planet before profit.'
Overthrowing systems and upsetting applecarts has a lasting appeal, taking many forms.
In the 1990s a young woman, described in a sympathetic profile by the Irish Times as "the convent-educated daughter of an RUC man from Ballymoney, Co Antrim" took a case for religious and sexual discrimination against the Ulster Unionist Party.
Patricia Campbell confounded many by taking her case soon after joining the UUs as a self-described political admirer of then-new leader David Trimble.
Ulster Unionist MP Mr William Ross told her, however, that he did not like her wearing her Claddagh ring in his office, a "Celtic symbol", and she should "go off and become a teacher".
She settled the case out of court, and began to run the party's new London office.
In 1996 the Belfast Telegraph reported that "the 31-year-old Oxford graduate" had received an anonymous letter addressed to "The token Taig", the worst abuse she disclosed at the time.
"I threw the letter in the dust-bin. If they had put their name on it, I would have been quite happy to write back to them."
She ran for the party in North Antrim in the 1998 Assembly election, and won 2,199 votes, 78 more than Joe Cahill. The Paisleys, father and son, came in at 10,590 and 4,459 respectively. The rest is silence.
What does defection consist of? In the eyes of many in their parties, Terence O'Neill, Brian Faulkner, Trimble, arguably Paisley senior, leaders who tried compromise and as a result lost their jobs; Mike Nesbitt who sacked himself, had abandoned the cause.
They were effectively defectors. Or 'traitors', as social media has damned the Labour leavers.
By contrast, said an analyst of his time, "the utter negativity of UU leader Jim Molyneaux ensured his long reign".
Did the Paisley phone ring in the night with only heavy breathing on the line, as befell others over the decades whom 'the Doc' cast out?
Most of the ousted leaders took public abuse, probably more on which they chose to stay quiet.
Many people who defied or criticised the dominant movements inside their communities, the IRA, UDA, UVF, are still not ready to talk.
The families of Paddy Devlin and Gerry Fitt took atrocious harassment for years after Devlin and Fitt opposed the hunger strikes.
SDLP to Sinn Féin defection? The vote's the thing.
Leaving the political, or religious, dispensation you are 'born into' has made many miserable, driven scores away, and killed some.
Observer columnist Andrew Rawnsley terms Westminster party-changers 'switchers', clearly a term of insult but a mild one.
Here a public move into the opposite camp has never been seen as a sincere change of mind and heart but as a hostile act, almost certainly gifting the enemy tribal secrets and ammunition.
Those 'born' Catholic of a certain age will recall, though perhaps with reluctance, that people 'born' Protestant who adopted Catholicism, though not necessarily regarded as the real thing, were awarded the title 'converts'.
On the other hand, cradle Catholics who 'turned' Protestant were 'perverts'. The Rawnsley word was 'switchers'; huh.
A positive if somewhat perverse final note.
That was some batch of defectors from Trimble's UUP; Jeffrey Donaldson, Timothy Johnston, Simon Hamilton, the young Arlene.
Churchill, who called his own shift from Conservative to Liberal and back again "ratting" and "re-ratting", was an exception.
Most Westminster switchers vanish. Having holed their original party below the waterline Jeff and Co swam straight to the top of the DUP.
And here we all are, waiting for Brexit, and the RHI inquiry.
