It gave rise to some of the most hideous characters of the modern political age and triggered immense fear — founded by various studies — through the worlds of business, agriculture, tourism, as well as a diminishing tolerance and a normalisation of far-right nationalism.

In a sporting sense, the ramifications have been keenly felt in London. Fielding GAA county teams is difficult for London, but the numbers speak for themselves.

In 2015, 493 inter-county transfers were into London. The year of the referendum, that became 378, a 23% drop.

Nobody is better qualified to assess the flow of labour than London senior football manager, Ciarán Deely.

“Since I became involved in 2015, I think because the Irish economy has been going relatively well in the last number of years, the volume of players coming over from Ireland to London has decreased significantly,” says the former Wexford footballer.

I don’t know the figures off-hand, but they have really fallen off a cliff-edge in the last few years. There is a feeling Ireland is booming, that Ireland is doing well and so people are staying. They are not coming over.

“In terms of Brexit specifically, it is hard to say that there is an actual effect from it. But I think certainly there would be a feeling that maybe London is not the place for people to emigrate to, at the moment.”

Blue-chip companies have spent the last three years levering themselves out of Britain, quite a few of them to Ireland.

Economic uncertainly, with the ghastly cast of the Conservative Party lurching from one disastrous negotiation to the next, is doing nothing for their fortunes on the Stock Market.

“If the financial services and things like that take a hit, then it affects us,” explains Deely.

“The profile of young Irish people has changed a lot. There’s not nearly as many of my players for instance are working in construction, which once was the case — bricklayers and carpenters, and so on.

"Now, it is people working in the financial district, teachers, engineers, and architects.”

Even that has slowed to a trickle. Last month, March 2019, just 10 players transferred into London.

For context, 182 transfers were sanctioned to Canada in March.

When Deely scouts the county for talent, the pool is becoming ever more shallow.

“And because of the profile of the people coming over now, it is more difficult to get a player to come out and play,” states Deely.

“If he is working in the financial district, if he is a lawyer, or even if he is a teacher in some of these new academies, it is a huge workload they have and their first priority is certainly not football or hurling.

“We struggle to get lads to commit at this stage. There are a lot of good footballers in London who don’t play for London.

"I know that’s always been the way, but it is probably more pronounced at the moment.

"People are working in different jobs and the London club scene at the moment, it is a real struggle for teams to field.”

Every crisis is an opportunity however, and the London senior football team is evolving into a self-perpetuating entity.

Deely says: “From our starting 15 in the league, it went from anything from four to seven players who were London-born.

“In terms of the overall squad of 30, there are probably about 13 players who were born here. There has been a concerted effort from the London County Board, the British Council to get coaches into schools.

We need young London-born players playing for London because there are not as many Irish lads coming over but also because it gives them (the London born players) an identity.

“And those lads are then going to be playing for London over a six- or eight-year period, whereas someone from Ireland, at some stage they can move back to Ireland.

"There’s been a lot of effort and from what I can see on the club scene, there has been a big effort in developing the underage.

"They are the ones that are fielding teams at the moment and that is relatively successful.”

Tír Chonaill Gaels have put enormous work into their underage coaching over the past 15 years.

They now have the Butler brothers Philip and Killian, Liam Gavigan and Ryan Elliott all staffing the county team.

Other clubs that have no youth policy, relying on enough players to reach them off the plane, are the ones struggling.

That’s not where the Brexit headaches end. Sean Hackett, a solicitor, originally from Ballygawley, Tyrone, has been living in Manchester for the best part of two decades and last year, completed his term as President of the GAA in Britain.

He can foresee enormous implications with information sharing in the event of a hard Brexit.

“This is a bigger issue, not necessarily for those people who are in Northern Ireland, England, Scotland, and Wales.

"Because what the government at Westminster said, is that they will pass legislation if there is a no-deal Brexit which will simply allow data to be passed from within the United Kingdom out of it, including Europe,” Hackett begins.

“Those are the existing rules that apply to data passing between any member states of the Union; the GDPR regulations that were brought in at the start of this year.

“The difficulty is that Europe would need to en-masse pass legislation which would allow data to pass out of Europe and by that, I mean the Republic of Ireland, into the United Kingdom.

"At the moment, I am not aware of any steps have been taken for any of that to happen.

“So while Westminster permits the passing of data out of the UK into Europe - they will legislate for it - there hasn’t been the same mirror approach taken from Europe.

“The question then is if data, be it relating to player injuries, membership, team sheets, all of that data, who is it going to pass from the Republic of Ireland out into Northern Ireland, England, Scotland, and Wales? That remains to be seen.”

Matters are further complicated by various administration arrangements.

The company Servasport have the contract for the membership database for the GAA worldwide.

However, the company and server is based in Belfast. If Northern Ireland falls outside of the EU, all the data that is held there on that server will be legitimate, but any processing of the data, particularly if it is coming from the Republic of Ireland out to the server in Belfast, could cause issues for how that data passes through the border, when it goes outside the EU.

Aside from all that, the most divisive political result in generations has had an insidious effect.

“Have I seen animosity towards people of Irish descent because of Brexit? You hear some people making comments about the Irish border being the problem. I keep reminding them of the point that it is not the Irish border in Ireland that is the problem. That isn’t the issue,” says Hackett.

“You do hear people making comments but it doesn’t really annoy me. Other people might get upset about it. It is my view that it has divided the British people terribly here.

"It doesn’t make a difference what party you vote for; it seems to be you are for, or against and it is a divisive point.

I suppose the big thing for people is a perceived erosion of their own national identity. Do people see themselves as European, do they see themselves as British? Other nationalities? 

"It depends on their outlook, if they embrace multiculturalism or if they see themselves as insular, looking inwards?”

Speaking at the launch of a new pitch project in Limavady, during the week, GAA President John Horan said on Brexit; “There’s no point us exercising energy on this at the moment… nobody knows what is going to happen.

"It would be a disaster to have to revert back to what went on before, but we will exert as much influence as we can. At the same time, I think it’s ultimately above us, in a way.”

Whatever about the public utterances, Brexit and its’ potential effects have been debated at the very heart of Croke Park committees.

They are aware of the dangers. But as for control?

A political movement that was pushed with the strapline of ‘taking back control’, has produced nothing but chaos.