Blue or Green? Billy or Tim? In Glasgow, your identity is reduced to a single imperative, something that your surname or the school that you attended reveals; or the football club that you support. Rangers or Celtic? The Protestant/Catholic division across this city, and the entire west of Scotland, is deeply felt enough to be relevant still, to still shape the behaviour of different generations, that it survives even the erosions of time.
The Old Firm clubs have come to be its most lasting, most forceful, on occasions even its most repugnant expression; nowhere else in world football is a rivalry based quite so clearly along religious lines, making it something unique, however thrilling or bleak it can turn. This enmity should have diminished, since it reaches back two centuries and has never been more under siege from changes in society, but Glasgow remains vulnerable to its old tribalisms.
Many of the segregation lines are now blurred: the city is increasingly secular, mixed marriages between Protestants and Catholics have never been higher, the middle classes are spreading in number and influence, and the old certainties of the Protestant working class voting Conservative and the Catholic working class voting Labour are now lost. These evolutions affect the followings of both clubs, so that the two supports have never been more homogenous, but they still cling to that solitary divide: religion.
Why can a football match between Rangers and Celtic end in a riot, or in a young man being stabbed to death because of the football jersey he is wearing? Why is it that players from outwith Scotland can become so inflamed that three Englishmen playing for Rangers – Terry Butcher, Chris Woods and Graham Roberts – ended up in court with Frank McAvennie, the Celtic striker; or that Paul Gascoigne could receive death threats after miming playing a flute (in reference to Orange Walks); or that Artur Boruc, a Polish goalkeeper, could be cautioned for gestures made to Rangers fans, including blessing himself? Why is it that the police report spikes in assaults, disorder and domestic abuse in the aftermath of Old Firm games? Or that paramedics and accident and emergency departments are inundated with drink and violence-related cases? Rangers and Celtic have become symbols for their communities, they provide a sense of identity that still relates to the sectarian divide that was once prevalent in Glasgow; in the songs and banners of the rivalry, a language of hate persists.
A kind of madness can arise on Old Firm days, something absurd but also deep-rooted and vehement. It is expressed in songs that glorify the IRA, or about being "up to our knees in Fenian blood". They are Scottish clubs, but the rivalry is shaped as much by Irish politics, immigration, unionism and republicanism, as religion (the Catholic church and the Orange Order once feared that the Troubles would spread across the Irish Sea).
Rather than Saltires, it is Union Jacks and Irish Tricolours that are the flags of these games. King Billy, Bobby Sands, The Sash, The Fields of Athenry; an Old Firm match is an untidy accumulation of history, spite, anger, and confusion. It is a football derby, like those in Milan, Buenos Aries or Istanbul, but one in which the rivalry has become entrenched in ancient hostility.
It is this tension that provokes such an intense environment that matches between Rangers and Celtic can become overwhelmed by the baggage carried into them (or make them compelling spectacles). In 1980, the Scottish Cup final between the two sides ended with supporters fighting on the pitch, and a subsequent ban on alcohol being served at football grounds. In 1999, when Rangers won 3-0 at Celtic Park to effectively clinch the championship, Hugh Dallas, the referee, was hit by a coin in the forehead, and individual Celtic fans tried to invade the pitch.
Football dominates – Istanbul is the only other city to house three stadiums with capacities over 50,000, but has a population of 13m compared to only 600,000 in Glasgow – because it is the sport of the working man. The grime of Glasgow's industrial past, the sweat, dirt, pride and poverty that were for so long the defining influences, still cling to every surface, however often they have been whitewashed. In the days when the Clyde shipyards and the narrow housing tenements of the Gorbals were domineering places, men would surge out at lunchtime on a Saturday and head straight for the football. The sport combined with drinking to provide the main sources of relief from the terrible grind of working life. And the city's two teams became the country's two major clubs by the same forces of history and culture that shaped Glasgow itself.
Celtic were formed in Glasgow's east end in 1888 by Brother Walfrid, a Marist monk, to raise money for the city's impoverished Catholic community, and also keep the youths away from the Protestant soup kitchens. As the club of the Catholics, Celtic's early glories prompted a form of indignation in Scottish society, as the country was resolutely, defiantly even, Protestant. Rangers were established in 1873 with no religious ties, but the club's size, success and location in the city's south side saw it become the club that the Protestant majority gathered behind to stand up to Celtic.
There were two waves of mass immigration from Ireland to Scotland; one mostly Catholic, in the 19th century, the other, in the 20th century, more mixed. The first influx prompted an anti-Catholic sentiment in the west of Scotland, a feeling that was exacerbated by the second, when workers arrived to find jobs in the Govan shipyards (in the 1920s there were even anti-Catholic political parties). Other British cities, such as Liverpool, Manchester and Cardiff, also received thousands of Irish settlers, and each suffered sectarian tensions and riots of their own in the early 20th century, only for them to fade out over time. The division remained in Glasgow because of its proximity to Ireland, allowing ease of travel and communication between the two countries, and Scotland's sense of itself as a Protestant nation.
There was a time in the west of Scotland when certain jobs and firms were widely known not to employ Catholics, a stance mirrored by Rangers' never having signed a high-profile Catholic player until Mo Johnston, the former Celtic striker, moved to the club from Nantes in 1989. Johnston was protected by a bodyguard, and some fans were aghast at his arrival, until he scored the winning goal in an Old Firm game. Now, Catholics have captained and managed the club, and a player's religion is no longer relevant.
Bigotry remains the background noise of Old Firm matches, even although the majority of fans no longer even practise their religion, and the encounters often teeter on the edge of malevolence. There are Celtic-only and Rangers-only pubs, supporters travel to Ibrox or Celtic Park on pre-ordained routes so that they cannot encounter each other, the matches kick-off at midday on a Sunday to prevent drinking beforehand, and the city tenses, so that you feel something fraught in the air. The derby is combustible because of the religious divide – which provides the means of expression, the context of the hatred – but also other factors.
Rangers and Celtic are Scotland's two dominant clubs, so their games inevitably influence the title race and the outcome carries a great weight of meaning; Scotland is so small, and the teams so big that it might be described as a national derby (more people followed Rangers to the 2008 Uefa Cup final in Manchester than attended the papal mass in Glasgow last year); there is an element of supporters living up to the game's reputation, so that the theatre of it – the noise is deafening and relentless – is self-fulfilling.
It is a football rivalry, but one that is darkened by its surroundings. Heavy drinking is rife in the west of Scotland, Glasgow has an entrenched gang and knife culture that treats violence as customary, and there are areas of such poverty, low life expectancy and unemployment that the sense of identity provided by Rangers and Celtic is clung to desperately. There are good and bad elements to both sets of supporters, and the flares of anger and resentment on the field are no worse than other derby matches. Alex Salmond, Scotland's First Minister, is not the first politician conspicuously to intervene, but his time might be better spent promoting anti-sectarian education (although many Scots believe that support for Catholic schools, which separate children from a young age, is a mitigating factor) and in tackling the problems of heavy drinking.
Sectarianism is no longer prevalent in Scottish culture, and religion no longer the central influence in people's lives. Yet the Old Firm game is blighted by the language of its enmity, the history it drags back into prominence. The football rivalry exists within this last remnant of hatred, so that the occasion reflects Glasgow's old antagonisms.
Richard Wilson is writing a book on the Old Firm called "Inside The Divide" that will be published by Canongate
The Old Firm: What they say about football's bitterest rivalry
"We've both got a lot of experience of this fixture and know that sometimes, in the heat of the moment, things can be said and words exchanged."
Celtic manager Neil Lennon after his touchline fracas with Rangers' Ally McCoist after last Wednesday's game
"The unedifying sight of two of the country's most recognisable and respected coaches engaged in an angry confrontation was not only unsavoury but exacerbated an already incendiary atmosphere inside the stadium and throughout the west of Scotland."
SFA Chief Stewart Regan after last Wednesday's violence
"There's a thing in a football ground called a 90-minute bigot, someone who has got a friend of an opposite religion next door to them. But for that 90 minutes they shout foul religious abuse at each other and we've got to handle in the first instance the 90-minute bigot."
Lawrence Macintyre, head of safety for Rangers FC
"I have never identified football with religion. Today there are probably more Catholics playing for Rangers than there are playing for Celtic. I agree there is still vitriol but you have to look at it in the context of where it is coming from. There are hardcore elements within the two sets of supporters. It works both ways."
Jack Ramsay, the head of the Orange Lodge in Scotland
"I would like to unreservedly apologise for my actions during the match at Celtic Park... I should not have made the gesture".
Paul Gascoigne apologies for his celebration in an Old firm game of playing a flute – a traditionally Unionist symbol
"First and foremost it was a football decision. We signed the player because he was the best Scottish player around and that is what mattered. Of course, it removed a cloud that hung above Rangers."
Rangers chairman David Murray on signing Catholic ex-Celtic player Mo Johnston (who nearly re-signed for Celtic)
"I looked him in the eye and didn't mince my words. I said, 'You mess me about and I'll fight you all the way. I'll make sure you never fucking play again'."
Then Celtic manager Billy McNeill on the same transfer
"I was stood near the dugouts when it all kicked-off and it was like an invasion of angry Bay City Rollers fans. They all seemed to have long hair and their scarves tied around their wrists."
Scotsman photographer Donald McLeod on the 1980 cup final that ended in a riot at Hampden Park
"This is like a scene now out of Apocalypse Now... We've got the equivalent of Passchendaele and that says nothing for Scottish football. At the end of the day, let's not kid ourselves. These supporters hate each other."
Commentator Archie Macpherson on the same match
Join our commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies