The variation in performance of the now very widely used glassy carbon electrode was identified as a point of concern soon after the material was introduced into electroanalytical chemistry. In essence, the exact nature of the glassy carbon, and indeed other carbon based surfaces, has their origin in the method (e.g. temperature) of manufacture, nature of pre-treatment and its history as an electrode (see for example and references cited therein). Accordingly, it seems likely that the widely variable electrode kinetic data associated with published studies on the [Fe(CN) 6 ] 3-/4-process (summarised in Eq. 24)