  We present high-speed, three-colour photometry of the eclipsing cataclysmic
variables GY Cnc, IR Com and HT Cas. We find that the sharp eclipses in GY Cnc
and IR Com are due to eclipses of the white dwarf. There is some evidence for a
bright spot on the edge of the accretion disc in GY Cnc, but not in IR Com.
Eclipse mapping of HT Cas is presented which shows changes in the structure of
the quiescent accretion disc. Observations in 2002 show the accretion disc to
be invisible except for the presence of a bright spot at the disc edge. 2003
observations, however, clearly show a bright inner disc and the bright spot to
be much fainter than in 2002. Although no outburst was associated with either
set of quiescent observations, the system was ~0.6 mJy brighter in 2003, mainly
due to the enhanced emission from the inner disc. We propose that these changes
are due to variations in the mass transfer rate from the secondary star and
through the disc. The disc colours indicate that it is optically thin in both
its inner and outer regions. We estimate the white dwarf temperature of HT Cas
to be 15 000 +/- 1000 K in 2002 and 14 000 +/- 1000 K in 2003.
