sentences:  The Metropolitan Police Service has reportedly been secretly using Cessna aircraft for a number of years that have been fitted with surveillance equipment capable of intercepting mobile phone calls and listening in on conversations.In 2010, "The Guardian" reported police forces and government agencies across the UK are exploring the potential of unmanned drones for covert aerial surveillance, security, or emergency operations.They said at least four forces – Merseyside, Essex, Staffordshire and British Transport police – have bought or used microdrones.