Introduction Adequate intraoperative lymph node sampling is a fundamental part of lung cancer surgery, but adherence to standards is not well known. This study sought to measure the adequacy of intraoperative lymph node sampling at a regional Thoracic Surgery Centre and a tertiary lung cancer center in the United Kingdom. Methods This retrospective study analyzed the pathological reports from NSCLC resections over the 4-year period 2011–2014. Adequacy of sampling was assessed against International Association for the Study of Lung Cancer recommendations of at least three mediastinal lymph node stations: station 7 in all patients, station 5 or 6 in left upper lobe tumors, and station 9 in lower lobe tumors. The influence of clinical variables (age, tumor T stage, type of surgery, and laterality) on adequacy of sampling and the effect of adequacy on overall survival were also assessed. Results A total of 1301 NSCLC resections were performed from January 11, 2011, to December 31, 2014. Adequate intraoperative lymph node sampling increased significantly from 14% (22 of 160) in 2011 to 53% (206 of 390) in 2014 (p = 0.001). Secondary analysis of clinical variables also revealed that patients with T1a or T4 tumors, those undergoing sublobar resections, those undergoing video-assisted thoracic surgery resections, and those undergoing left-sided resections have significantly higher rates of inadequate lymph node sampling. Overall, there was no statistically significant difference in survival between patients with adequate versus inadequate intraoperative lymph node sampling or when survival was stratified according to overall stage. There was worse survival in inadequate sampling for patients with pN2 disease than for patients with pN2 disease and adequate sampling. Conclusion This study provides a much-needed benchmark of current thoracic surgical practice in lung cancer in the United Kingdom and important granularity to facilitate changes to improve adequacy of staging.