Rankin (1990) attempted to distinguish between one- and two-pole interpulse models for PSR 1929+10, and, despite the evidence to the contrary (Lyne & Manchester 1988; Phillips 1990), argued that it was probably a two-pole interpulsar on the basis of its narrow components. If it is a two-pole interpulsar, its interpulse has just the right width to be a core component—that is, , the angular width of the polar cap. However, PSR 1929+10 was virtually the only well studied pulsar of any profile class which could not be comfortably fitted into the quantitative description of the conal emission geometry as discussed by Rankin (1993 a,b). The problem arose due to the narrow dimensions of the conal component pair in this pulsar, which do not fit well with the inner and outer cone properties followed by many pulsars. In order to explore this issue further, we use the technique of constructing partial ‘mode-separated’ profiles corresponding to the primary and secondary polarisation modes.