Largest, and that agency has nothing to do with Freo's MarComms due to the obvious conflict of interest. I believe these guys do it: http://blockbranding.com/work/fremantle-dockers/
You are correct about their being a potential conflict of interest - though I know from first-hand experience there are ways around that kind of problem, and that many agencies have done so in the past (...please note I am not saying the Brand is engaged in a COI in this instance... only that similar issues have arisen at large agencies in the past, and that agencies regularly seem to 'find a way' to deal with the issue).
For the record, I reckon Mark Braddock and the guys at Block did a very good job with Freo's rebrand / corporate livery, though AFAIK I don't think Block did Freo's A/V work as well - not really their area I would have thought.