Its popularity will be hard to argue with but the relevance and effectiveness of a royal commission into banking, as announced by Australia's Labor opposition, may be dubious.  Any inquiry will start off informed by its terms of reference yet may soon be derailed by the energetic efforts of the wingnuts who consider they've finally found a platform for justice. If elected, Labor probably will go on to establish the banking and financial services royal commission it has pledged.  Cynics will wonder if it will ever finish the job. Consider the work of the four or five post GFC Senate committee inquiries into aspects of banking. The Senate Economics Reference Committee has done most of this work, with one on small business finance issues; a second on banking competition; a third on post-GFC banking sector; a fourth into the performance of the Australian Securities and Investment Commission and its response to banks' mis-selling of investment loans before the GFC; a fifth into credit card interest rates; a sixth into agribusiness managed investment schemes; and a seventh into the impairment of customer loans and the forced sale of propertyYet one more inquiry is underway, which might be styled as the forum to "get" CBA one more time over Bankwest, an exercise struggling to overcome the weird theory that Commonwealth Bank maximised profits by maximising losses.Anyway, if there is to be a banking royal commission, may it shine the spotlight on three of Banking Day's favourite topics: the industry cost structure (to quote from a 2015 research report by our only known ally in this cause, Jonathan Mott of UBS, "while the major banks look efficient from a cost-to-income ratio perspective, their absolute cost base has blown out to A$37 billion [a year] .... this appears to be an astronomical amount of money to run a banking system across Australia and New Zealand."); the post 1980s financial deregulation industry structure, featuring a wave of demutualisations, privatisations and then wealth and banking mergers, which was was a topic David Murray's panel for the recent Financial System Inquiry found of little interest; and uncovering all the facts on the Australian banking system's near death experience in 2008, a study bound to be disconcerting for all those that have hooked their reputations to the BS and bulldust story of Australian exceptionalism during the great recession.