Sorry to burst your dad's bubble, but McClair (from Airdrie) was a 'Hoops' fan through and through.
Don't think Joe was either - though certainly grew to have a deep affection and affinity with the club.
Think I read somewhere that Johnny Gaghan - though from Glasgow used to come to games with his Uncle, prior to signing and claimed to have been a supporter.
Gary Mac seems to divide opinion with those who went to school with him - some claim he was a 'blue-nose' others that he bled 'Claret & Amber' - he does pledge his allegiance to Motherwell when appearing as a pundit