What is status of B504 now there is no through traffic from Judd Street to Euston Road? The presence of both secondary & tertiary segments looks odd. Also even if Judd St is accorded tertiary status this surely doesnt apply beyond Bidborough Street. If it hasnt officially lost it's B-road status then the ref ought to stay. 

At a guess the Hunter St, Tavistock Place junction is a better place to terminate the secondary status, but I'm still unsure if the rest merits even tertiary.