Comment: Time for another purge at NAB 16 April 2015 3:54PM Ian Rogers Comment, Other topics Middle management is taking the blame at National Australia Bank for the misdeeds of staff in its shameful approach at Clydesdale Bank over its handling payment protection insurance policies in the UK.But responsibility surely stretches further than that.In January, David Thorburn opted to stand down after almost four years as Clydesdale Bank's CEO and one must wonder if the PPI affair informed that choice.David Duffy, formerly from Allied Irish Banks, is his replacement.Where else does the responsibility lie?Michael Chaney at last year's AGM spelled out plans to stand down from the board of National Australia Bank in 2015.Perhaps Chaney's time is already up.