Every organisation has ghosts. Not shrieking spooks exactly, but the sort of behavioural ectoplasm that clings to companies long after change has supposedly swept through. Spectres of past successes haunt the board and frighten investors, while staff in pursuit of new goals have to wade through psychomagnotheric slime to get there.

Ghost structures and habits are particularly persistent at established companies. Whoever takes over at UniCredit will find some skeletons: the Italian banking group, which just started a search for a new chief executive, goes back nearly six centuries and so, probably, do some of the ways it works. But newer groups also need ghostbusters. Twitter, which continues to tinker with its hierarchy and misfiring model, is a good example of a company still spooked by the spirit that first enlivened it. Exorcists should always be on standby at start-ups, where behaviour that seemed fresh in the first phase of growth often reeks of recklessness by the second or third round of funding.

Two big problems stand in the way of ghostfinders-general. As leaders of the organisation, they were often the champions of the type of behaviour that now holds it back. “We’re asking them to change the things that got them there in the first place,” says Jonathan Trevor of Oxford’s Sa?d Business School.