Fêted by Rod Stewart and lauded by England manager Roy Hodgson, the Green Brigade - Celtic's group of "self-styled ultras" or hardcore fans - appears to have lost its war with the club and the goodwill of fellow supporters.
In the last month, the Green Brigade's love/hate relationship with Celtic's hierarchy has become one of just hate. One of its politically charged banners landed the club with another fine from European football's governing body last week, and its association with the damage at Motherwell's Fir Park stadium caused by setting off pyrotechnic flares and the breaking of seats is likely to see the club's place in the experiment of Friday night football pulled.
As a result, more than 120 of the Green Brigade's members and associates are suspended from Celtic Park, and its notorious Section 111 within the ground has been broken up.
In the popular imagination, they have had their status as Scottish football's bête noir confirmed, shifting from a noisy, colourful, provocative and politically confrontational group to essentially hooligans with a fondness for Irish Republican paramilitaries.
Police Scotland, determined to make the contentious Offensive Behaviour at Football Act work, and whose officers have had regular brushes with the Green Brigade, could not have wished for better headlines.
It all seems a long way from their pivotal role in making nights like last season's win over Barcelona among the best in living memory.
"Celtic have done what the police couldn't do and that's put the game beyond repair for us," one member of the Green Brigade told the Sunday Herald.
"Will it end the group? Well, it could go either way, limping on and people could then chuck it. The moment might have gone. Lots of things are mounting up. The harassment from the cops and Celtic takes its toll.
"But when we got this thing going we were underground. We were raw. But we lost that. We went from one end of the spectrum to being in Rod Stewart's book. The kids have ripped it up in the last weeks. I think we all have."
The Green Brigade has a core of around 80 members, a decision-making inner circle of around 30 and a wider associated circle in its section within Celtic Park of around 350 people. Its successful underground merchandising operation would give the impression of a much larger group, however.
Police Scotland admits the group are not "casuals". It has dismissed links with illegal groups in Northern Ireland, but expressed concern about the group's use of pyrotechnics, the "vulnerability" of younger members and breaching the Offensive Behaviour Act via songs the force sees as falling foul of the legislation.
Since the introduction of the legislation, many of the Green Brigade's members and associates have been arrested and brought to court for a breach of the act.
The Green Brigade was formed by no more than half a dozen members of a previous singing section, the Jungle Bhoys, who became disillusioned with that group around 2005 and wanted something more political which spoke to the Ultras scene of clubs such as Germany's St Pauli or Livorno in Italy.
Soon they were active at anti-racism and STUC events, but still numbered only around a dozen marching behind their own banners. But when Celtic gave over a section of its ground to the burgeoning group, numbers started to snowball.
"By the time it's 2010, the group gets Section 111 and we realise we've a movement on our hands.
"How do you get in? Well, you've got to turn up for games for starters. Then there's paint nights, helping out with banners, setting up before big games in the ground. It's almost like having another job and a lot of work goes into it away.
"To get in - it's almost like an interview with people who are in your wider company. The group's looking for people with different opinions, but on the three main topics."
But controversy was never far away. A Remembrance Day banner demanding "No bloodstained poppy on our Hoops" brought widespread condemnation, and a Uefa fine for "illicit chanting" following the singing of songs referring to the IRA during the team's Europa League run in 2011 was met with the notorious "F**k Uefa" banner at a subsequent game.
But for all his condemnation, Celtic's chief executive, Peter Lawwell, kept the group on board, an acknowledgement of its input to the atmosphere at an otherwise moribund Celtic Park. Manager Neil Lennon also made a point of singling them out for praise when presented with the League trophy.
The Green Brigade member the Sunday Herald spoke to stands by their banners, including the ones linking IRA hunger striker Bobby Sands to William Wallace. However, several members of the Green Brigade have faced criminal action for singing the anthem Roll Of Honour, which commemorates the hunger strikes through the line "England you're a monster". They argue that Flower Of Scotland carries the same sentiment. He said: "The group was becoming part of the Celtic Park experience, part of the day trip; the section isn't as hardcore as many think.
"But the banners over the last few years haven't been about pushing the boat out and trying to annoy the club. Every single one of the banners had a deeply held belief and a point behind it.
"Like the Bobby Sands and William Wallace banner. A lot of people were scratching their heads. Even other Celtic fans were asking what this was about. But we knew. Anyone affected by the Offensive Behaviour Act knew. And if your audience is based around people getting arrested at the football, what better audience to make your point in front of?
"Forums and fanzines have had their day. It gets to the point where things build up a head of steam. The Offensive Behaviour Act came in and while people had reservations how it would affect them, it was not until it came in that we knew just how.
"And that's not just the group. It's those who were in our wider area and wider social circle. Away games is where the arrests are. Cops picking up easy targets, daft drunk kids who don't realise the consequences of their actions and whose lives can be ruined for singing a song with their mates.
"And we get the label we do because people in Scotland aren't willing, even now, to accept Irish Republican views as an acceptable political ideology. Back in the days of the Jungle, no-one was really picking up on this, but the last few years have thrown up a generation of tut-tutters who sang much much worse [songs] than we do now."
If the knock-out blow was the Motherwell game, then the Green Brigade admit they "took their eye off the ball". The emergence of a group of affiliated young Turks in the last year, the Style Mile Vandals (SMV) brought the edge of drunkenness and hooliganism to Celtic away fixtures. So who are the SMV?
"Well, they're kind of the naughty wee brother who got kind of carried away. They've been on the go about a year, are younger kids and into graffiti and stuff. These are the guys out late at night putting up stickers and spray painting.
"The Union Bears [Rangers' 'ultras'] have something similar. But there's a huge difference between the SMV and the Green Brigade, even if there's an overlap of a few members.
"The Green Brigade kind of don't want the notoriety as individuals; the SMV want to be the big boys. They see themselves as a group within a group and the Green Brigade are annoyed they've been pursuing their notoriety.
"My view? The recent pyro stuff hasn't just been the SMV and the kids around the group. It's easy enough to find online and it's also cheap enough to find online and it's also cheap enough for anyone to buy. However, a lot people need a bogeyman to blame."