UKOLN”s QA Focus project made use of the log validator tool developed by W3C to identify HTML validation problems on the QA Focus Web site. The tool helped to prioritise the fixing of problems by reporting on the most visited invalid pages. The tool was integrated within a quality assurance framework, which ensured that invalid pages were not only fixed, but the underlying causes of the problems were addressed. A testimonial about use of the tool has been published on the W3C Web site.