Climbers scaling a mountain frequently suffer the temptation to look down and panic. Sheikh Mansour bin Zayed al-Nahyan has encouraged others to do the same, after booking a £1.46bn (€1.7bn) profit on convertible notes in Barclays, bought last November as part of the bank's refinancing exercise.

At this point, Sheikh Mansour's footwork is rather more impressive than footballers at his Manchester City club. Shares in Barclays are down nearly 20%, amid fears he knows something about the state of Barclays that the rest of the world does not.