IT IS a sprawling, unseen, unglamorous industry that is hard to define and harder still to measure. Outsourced facilities-management firms clean offices, guard premises, feed students, manage heating and lighting, move prisoners from cell to workshop, and so on, for customers who prefer to focus on their core activities.

Employing millions, outsourcing firms have combined revenues that some put as high as $1 trillion a year. The market is most established in Europe and North America, though it is on the rise in Asia too (see chart). Now the structure of the business is changing, as firms that used to specialise in one sort of outsourced service increasingly aim to be all things to all men, and trip over each other in the process.