  We have reconstructed the temperatures and surface densities in the quiescent
accretion disc in HT Cas by performing a "Physical Parameter Eclipse Mapping"
analysis of archival UBVR observations. Using a simple hydrogen slab model and
demanding a smooth, maximally artefact-free reconstruction, we derive a formal
distance to HT Cas of 207 +- 10 pc, significantly larger than the 133 +- 14 pc
we derive from a re-analysis of the data in the literature.
  We argue that the larger derived distance is probably incorrect but is not
produced by inaccuracies in our spectral model or optimization method. The
discrepancy can be resolved if the emission regions on the disc are patchy with
a filling factor of about 40% of the disc's surface. This solves the problem
with the high effective temperatures in the disc -- reducing them to around 6
500 K within a radius of 0.2 R_L1 -- and reduces the derived temperature of the
white dwarf and/or boundary layer from 22600 to 15500 K.
  We discuss several possible sources of the chromospheric emission and its
patchiness, including irradiation of the disc, thermal instabilities,
spiral-wave-like global structures, and magnetically active regions associated
with dynamo action and/or Balbus-Hawley instabilities.
