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Introduction Optical diagnosis (OD) with a resect-and-discard strategy for diminutive polyps enables real-time endoscopic characterisation, photo-documentation, and immediate resection without histopathology. This supports more sustainable, efficient, and cost-effective practice while maintaining diagnostic quality. In 2023, the NHS Bowel Cancer Screening Programme (NHSBCSP) approved OD for implementation, with national roll-out commencing in 2024. This study provides an early evaluation of the first 18 months, examining training uptake, accreditation outcomes, quality-assurance structures, and early estimates of time and cost savings.Methods All 520 screening colonoscopists were invited to complete a two-stage national OD accreditation pathway.Part 1 comprised a national training day covering classification systems, high-confidence criteria, and photo-documentation standards, with pre- and post-course assessments of 120 polyp images. Accreditation required ≥85% accuracy for high-confidence calls and ≥50% of calls made with high confidence.Part 2 involved supervised in-vivo assessment at each colonoscopist’s base hospital, requiring 20 consecutive high-confidence OD cases. Assessment included photo-documentation quality using the 3C score (clean, complete, correctly focussed) and diagnostic accuracy versus histology. A pass required ≥90% adequate photo quality and ≥85% accuracy.Successful candidates were accredited to perform OD with resect-and-discard in screening practice. Re-accreditation is required every two years via an online assessment. Each screening centre appointed an Optical Diagnosis Champion to support accreditation, monitoring, and quality assurance.Results Between March 2024 and October 2025, six national training days were delivered. Of 520 colonoscopists, 501 (96%) completed Part 1, and 451 of 501 (90%) passed. By October 2025, 276 of 501 (55%) had completed both stages and were fully accredited.Optical Diagnosis Champions were appointed at 62 of 64 screening centres (97%).By 31 October 2025, 32,919 diminutive polyps had been resected and discarded without histopathology, generating an estimated cost saving of £1,218,003 (£37 per specimen) and approximately 10,973 hours of histopathology reporting time saved. Further gains are anticipated as accreditation increases.A further national training day is planned for February 2026, after which Part 1 will transition to an eLearning format.Conclusions Early implementation shows high engagement with OD training across the NHSBCSP, with over half of trained colonoscopists accredited and delivering OD in practice. Substantial early cost and workforce efficiencies are evident. With strong local QA infrastructure and expanded training access, full national implementation is expected by 2027.