Nothing will capture the complexity of the Glasgow-Irish relationship than the chorus of boos which will, as Gordon Strachan predicted, rumble around Celtic Park next Friday night whenever Aiden McGeady touches the football.

They might be booing him because he chose Ireland over Scotland. Or because he is ex-Celtic. Or because he is not still Celtic. They may boo him because he is not of Rangers – and all which that entails. They might just boo him because he is good.

“Pantomime booing,” Strachan called it and hoped that it would be no worse than that. McGeady is one of the touchstones of what will be an evocative night when Ireland and Scotland meet at Parkhead.

For decades, the stadium has been a shrine for Celtic’s legion of Irish fans. McGeady’s paternal grandparents came from Gweedore in Donegal, the county which wears its Glasgow Celtic allegiances most vibrantly.

Emotional energy

Friday night’s match – Ireland’s first competitive match in Scotland since Mark Lawrenson’s February evening bolt in Hampden Park in 1987 – will concentrate much of the historical and emotional energy of the Glasgow-Donegal connection in the streets and bars around the stadium.

“I think it’s a match that is going to test a few loyalties,” says Paul McGuire, a Glaswegian who, while digging through family history, found that he was related to one of Celtic’s founder members, a Donegal man named Joseph McGroary. His great-grand-nephew stumbled upon their relationship and learned that McGroary had attended secondary school, strikingly unusual for the son of Irish emigrants, and had later qualified as one of the first Catholic lawyers in Glasgow.

His employer was a Joseph Shaughnessy, a key figure in the foundation of Celtic. McGroary later vanished off the radar, reappeared in Brooklyn and spent his last years back in Donegal.

“We spoke to a gentleman in Mountcharles last week who remembers meeting him. He recalled him as a kind of svelte man with a bowler hat and shirt and tie and he was very prominent in town.”

McGroary’s graveyard is in Frosses and the Donegal Celtic Association is working with the club to come up with a new design for a headstone acknowledging his role. For McGuire, the discovery was a fascinating and pleasing affiliation to the football team he had followed all of his life.

But the more he thought about, the more it made sense. The longer he lives in Glasgow, the more evidence he sees of the fingerprints – and footprints – between the city and Donegal.

Sell out

“My wife, too, has Donegal connections. And there are just so many people in the south side of Glasgow for whom that is true. The Donegal papers are in the shop and sell out quickly. You go to Celtic Park and you still see the buses coming over from the county.

“And I think it is the kind of place I would like to go over to and take my wee boy. There is a heartache about the fact that they had to leave such a beautiful place to live here in what was real squalor. And funny, a lot went back to Donegal because the children were dying here. Even during the All-Ireland final, you would see the jerseys and flags outside so many of the bars.”

Packie Bonner is the most celebrated of Ireland’s Celtic players. By the time Sean Fallon, who was Jock Stein’s assistant, came to watch Bonner play, the young goalkeeper was already well versed in the lore of the club.

“Sean made the first contact with myself. We never saw Celtic play live but everyone just supported the club and so many people had come over here to work that the team was like a release valve. I remember my next-door neighbour, who was my godfather, had a huge big photograph of the Lisbon Lions team in his hallway and I could name all the players even though I had never seen them play.”

When members of that 1967 European Cup-winning team visited Donegal in 2007, they were keen to make the pilgrimage to visit the home place of Patsy Gallaher, the dynamic Celtic player of the 1920s who was born in the most humble of circumstances in Donegal.

“Yeah, in a workhouse in Milford,” says Adrian Gallagher. “I’m sure that was partly because times were tight but also because it would have been the closest medical facility in the area.”

Gallaher was a sensational player for Celtic for 15 years after his debut in 1911 and remains the club’s sixth highest scorer of all time. He didn’t maintain much of a connection with Donegal in later life but Gallagher is certain that word of his exploits would have made it back at that time.

“Oh, they would have had to have known about him because the seasonal emigration was huge. A lot of people spent their lives moving between Glasgow and Donegal.”

Denis Doherty is, literally, a son of that constant traffic, born in Glasgow to Dungloe and Falcarragh parents. He rarely misses a Celtic game, setting out with the other regulars from Letterkenny at 4am for home matches.

“We catch the ferry at Larne, get to the match and are back by midnight,” he said on Thursday from Bucharest, where he watched Celtic’s Europa league game against FC Astra.

“The connection goes across the full spectrum of our supporters. They are often second- and third-generation and Celtic is more than just a football team to them. It is a big family.”

In certain areas of Donegal – Gweedore and and Rosses – the Celtic mythology is so deeply ingrained that youngsters grow up supporting the team without really questioning why.

“I was, yeah, I was always Celtic,” says Declan Bonner, the former Donegal All-Ireland medal winner and current minor manager, who came tantalisingly close to signing for the club as a teenager.

“Rosses community school had huge Celtic connections and was aware of all these players, but you weren’t seeing them as much on telly. You were getting the results every Saturday and people would go back and over to watch them and there was just an awareness and sense of belonging about the club.”

Bonner only started playing football at 13 but progressed so quickly he became captain of the Irish under-17 team. For most of his Leaving Cert year, he was hopping back and forth to Glasgow to train with the reserves. He stayed with Packie Bonner, who was just breaking into the first team.

Pre-season

“Billy [McNeill] said we could offer you a contract in the morning but he said to go back and get what he called “your finals” and we will bring you back for pre-season in late June. Then the word came through that Billy had left for Manchester City. So there was a new set up there. And I went from getting organised to going over, to Brian McEniff calling me into the panel for the 1983/84 league. That was basically it. There wasn’t much time to dwell on it.”

For Declan, the experience was a rushed and wonderful experience. He had trained several times with a Celtic squad featuring Charlie Nicholas, Danny McGrain, Davie Provan and Roy Aitken and was brought along to Old Firm derbies.

“I would have been willing to sign my contract but it was coming to the end of the season anyhow and there was logic in the point. It didn’t materialise and I suppose it wouldn’t have been anything like as organised as it would now. I do believe that if it’s for you, it won’t pass you. I still continued to play soccer. It would have been a great opportunity. Still, I wasn’t ever a six- or seven-year-old dreaming of playing for Celtic. It just happened. I think my parents were probably delighted I ended up playing Gaelic football as that was more important to them.”

Packie Bonner reckons that the Rosses man was particularly unfortunate. “When you have a young fella staying with you, then you are always hoping and trying to find out where he stands and my enquiries to John Kelman, the chief scout, led me to believe that, yeah, they were definitely going to sign him. He was a good football player and they were going to sign him. But that is football. And maybe it was better for Declan because he might have stuck over here, maybe not making it and getting frustrated and losing out on a fantastic career with Donegal.”

Almost a decade later, Declan was attending an All-Ireland banquet in Glasgow with Tony Boyle and they called into McNeill’s bar. “He [McNeill] was there and he remembered my time there and we sat down and he basically gave me his side of the story, which was that he couldn’t let the Manchester City opportunity pass.”

But the lure of Celtic was and remains huge for any Donegal youngster hoping to cut it at football. Packie Bonner became such a folkloric figure with Celtic and Ireland that the Artane Boys band marched around the stadium on the day of his testimonial.

By then, Celtic games were on television more frequently, impressing the next generation of Donegal footballers like Shay Given, who with his father took the ferry from Larne to Glasgow to serve his apprenticeship. It was a period he recalled as being singularly tough experience in a 2003 interview with this newspaper. “It was all an adventure until we signed and then they went home and I was alone in Glasgow. The worst was the nights in the digs.”

Given was offered a contract but also had attracted the notice of Blackburn Rovers scouts on a tour of Sweden with the Scottish club and they were quick to offer more generous terms. Still, Given remained a Celtic fan.

“All along the western seaboard there was that pattern of going over there to work,” says Declan Bonner. “It is something that has been going on for 100 years really. Even when I was coaching in Gweedore, the number of people going over every weekend is staggering.”

The sense of shared accomplishment which followed the appointment of Jim McGuinness to Celtic’s coaching staff in 2012 marked a full revolution in the journeys taken from Glenties to Glasgow over a century.

Mass movement

Patrick Magill's bleak classic Children of the Dead End, chronicling his life in early 20th-century Glasgow and McGuinness's high-profile arrival a century later represented journeys at opposite ends of the spectrum. The pattern of mass movement between the places has stopped now but they have become inextricably linked.

“The second- and third-generation ties are so strong that it will always exist,” says Packie Bonner. “For instance my son Andrew [who has played for Ireland youth teams] was born in Glasgow and feels very Irish.

“So I think there is going to be a lot of split allegiances for Scotland and Ireland in Celtic Park next Friday night. I know Gordon [Strachan] wanted to keep the Irish allocation to 3,000 fans. But the truth is that there will be Irish dotted all over the place.”