Archaeologists became heavily involved in the planning process after 1990, when policy guidance was first published requiring the investigation of possible heritage sites as a precondition for planning permission. Developers pay for the archaeologists’ investigations and generally consider this to be a straightforward cost from which they receive little direct benefit, apart from planning permission. Without the regulations developer demand for archaeologists’ services would be much lower – although some developers (those with a particular interest in the field, those who own sites of particular interest, or those who see it as a public relations tool) would still commission work.