The World Health Organisation (WHO) Surgical Safety checklist is an evidence-based tool shown to reduce surgery-related morbidity and mortality. Despite audits showing 96% checklist compliance, our hospital had 3 surgical never events in 10 months, 2 of which were in orthopaedics. By March 2018, the authors aimed to achieve 100% compliance with all 5 sections of the WHO Five Steps to Safer Surgery bundle for all surgical patients. Additionally, the authors aimed to assess the impact of the quality of bundle delivery on preventable errors related to human factors. Quantitative assessment involved direct observations of compliance in theatres. Qualitative data in the form of rich, descriptive observations of events and discussions held during checklist delivery was analysed thematically. Interventions included trust-wide policy changes, awareness sessions, introduction of briefing and debrief proformas and documented prosthesis checks. For elective surgeries, checklist compliance increased to 100% in 4 of 5 sections of the bundle. The incidence of reported preventable critical incidents decreased from 6.7% to 2.4%. A chi-squared test of independence demonstrated a significant relationship between the implementation of changes and completion of the checklist, X2 (1, N = 1019) = 25.69, p < 0.0001. Thematic analysis identified leadership, accountability, engagement, empowerment, communication, and teamwork as factors promoting effective checklist use. Our findings highlight the benefits of a qualitative approach to auditing checklists. Exploring the role of human factors and promoting staff awareness and engagement improves checklist compliance and enhances its effectiveness in reducing surgery-related adverse outcomes.