The time between leaders is a dangerous one. In medieval times they’d gloss over it by having messengers shout ‘The King is dead! Long Live the King!’ Which roughly translates as: ‘Yes, the king may have snuffed it, but don’t even think about getting uppity because the new one has already moved into the castle and is busy sharpening his favourite axe.’ BC&F Dentsu chief executive Paul Catmur takes a look at industry’s changing guard.