Police recruiting private security: 'It leaves the thin blue line a lot thinner'

Two police forces are inviting bids from security companies wanting to become involved in areas such as investigating crimes and patrolling neighbourhoods.

West Midlands and Surrey police say they need to save money and most core police work, including arrests, would still be done by uniformed officers.

Michael Gradwell, a former detective superintendent, spoke to the BBC about the work that private companies could do for police.