To drive the subsequent development of the ALADDIN counter-drone system a User Requirements Workshop has been organized in St Albans (UK) by the UK Home Office – Centre for Applied Science and Technology (CAST). The workshop, restricted to Law Enforcement Agencies (LEAs) and ALADDIN End Users (AUG), was attended by delegates of 9 organizations (CAST, ACCIONA, FADA CATEC, French Police Prefecture, HMPPS, Italian Police, KEMEA, PJ Portugal, Spanish National Police). Example UAV threat scenarios were presented to elicit user requirements. A session, led by CAST, was used to capture the full range of users and systems interacting with the C-UAV system. Another session, led by KEMEA, collected useful input from attendees on relevant Concept of Operations (ConOps).