Emergency department (ED) crowding has significant adverse consequences, however, there is no widely accepted tool to measure it. In a prospective study involving ED nurses and clinicians we validated the National Emergency Department Overcrowding score (NEDOCS) which uses routinely collected ED data. This work was presented in Prague at EUSEM and published in the EMJ: doi:10.1136/ emermed-2019-208836. From 905 sampled hours, 448 paired observations were obtained. NEDOCS demonstrates good discriminatory power for clinical perception of crowding. However, prior to implementation, determining individual unit ED cut-off point(s) would be important as published thresholds may not be generalisable. We have subsequently been awarded a national grant award from the Royal College of Emergency Medicine (RCEM) to further explore this work. This work would not have been possible without the help of Informatics experts Shu Shi and Mark Dennis for electronic database extraction, calculation of scores and automation of data collection