You have just done your own argument in by describing the term as to describe a rivalry between two football clubs and their fans The Old Firm rivalry was between Celtic FC  and Rangers FC  The Club currently playing at Ibrox is not the Club formed in  so how on earth can the Old Firm term be used as anything other than in the past tense Would people reporting sightings of Elvios Pressley on the Las Vegas strip In Common Speech be regarded as FACT that he was alive I rest my case This example of page hijacking by fans of Rangers FC  has made Wikipedia nothing other than an embarrassment as a source of information