Key Points • Clinical N3b staging is defined as unequivocal and unambiguous signs of extra nodal extension (ENE), such as skin involvement, muscle invasion or nerve dysfunction, supported by radiological evidence. • There is a paucity of studies determining interobserver reliability of clinical detection of overt ENE. • A prospective comparative cohort study assessing 12 Head and Neck surgeons’ inter-observer agreement in detecting the components of overt ENE. • We reveal high surgeon agreement in the ability to detect lymph nodes, the presence of skin involvement and in surrounding nerve involvement. • Variability of surgeon assessment was seen in the assessment of overt muscular involvement.