Choosing the right moment to quit is arguably the hardest judgement call in management — just ask Arsene Wenger. The same goes for corporate boardrooms; and if Ross McEwan wishes to secure his legacy as the leader who restored order to Royal Bank of Scotland, his next significant act will be to offer chairman Sir Howard Davies his resignation.

When he took over in 2013, the Kiwi's in-tray resembled an Everestian mountain — unresolved fines, a dysfunctional management team and the mistreatment of personal and small business customers for which only board members’ preoccupation with a multitude of crises could excuse the absence of swift and decisive action.