  PSR J0742-2822 exhibits two distinct emission states that are identified by
discrete changes in the observed pulse profile. These changes have previously
been shown to correlate with changes in the derivative of the pulse frequency.
In this paper, we use observations with the Parkes radio telescope at a centre
frequency of 1369 and 3100 MHz to produce high phase resolution polarisation
profiles for the two modes and perform a detailed study of the correlation
between observed pulse shape and spin-down rate. We find no correlation for at
least 200 days prior to a glitch in the pulsar at MJD 55022, following which
the correlation becomes strong. This suggests a link between the emission state
switching phenomenon and glitch events. We discuss the possibility that
emission state switching is driven by the interaction between the magnetosphere
and the interior of the neutron star.
