It’s Old Firm week, unfortunately for Rangers fans though, there are no tickets for Parkhead thanks to Celtic digging their heels in on ‘safety’ grounds. This doesn’t mean that there won’t be a presence in Glasgow as the build up to one of the most important derbies in years gets underway. At Ibrox on Sunday, Rangers fans group the Union Bears struck first blood and the story behind their Green Brigade heist is as simple as it is hilarious. READ MORE: Rangers vs Celtic: Old Firm all-time record attendancesRangers fans group the Union Bears get one up on Green BrigadeSince the prevalence of fan…