Undercover reporter warned to be carefulTo play this video you need to enable JavaScript in your browser.This video can not be playedUndercover reporter warned to be carefulCloseWatch the full Panorama documentary on BBC iPlayer here.SectionNewsPublished1 OctoberShareclose panelShare pageCopy linkAbout sharingRelated topicsPolicingFollow Policingclose panelYou are now following PolicingUpdates from your News topics will appear in My News and in a collection on the News homepage.Read description