  We have extended our H alpha objective prism survey of 8 low-redshift
clusters (viz. Abell 262, 347, 400, 426, 569, 779, 1367 and 1656) to include a
complete sample of early-type galaxies within 1.5 Abell radii of the cluster
centres. Of the 379 galaxies surveyed, 3% of E, E-S0 galaxies, 6% of S0s and 9%
of S0/a galaxies were detected in emission. From a comparison of cluster and
supercluster field galaxies, we conclude that the frequency of emission-line
galaxies (ELGs; W_lambda >/= 20 angstroms) is similar for field and cluster
early-type galaxies. A similar result has previously been obtained for galaxies
of types Sa and later. Together, these results confirm the inference of Biviano
et al. that the relative frequency of ELGs in clusters and the field can be
entirely accounted for by the different mix of morphological types between the
differing environments. Detected emission is classified as `compact' or
`diffuse', identified as circumnuclear starburst or AGN emission and disk
emission respectively. By comparing spectroscopic data for cluster early-type
ELGs with data for field galaxies from the Palomar Spectroscopic Survey of
nearby galactic nuclei, we demonstrate there is modest evidence for an
enhancement of compact HII emission relative to AGN emission in the early-type
cluster ELGs as compared to the field. For the cluster early-type galaxies,
compact HII emission correlates strongly with a disturbed morphology. This
suggests that, as for later type cluster galaxies, this enhanced compact HII
emission can readily be explained as an enhancement of circumnuclear starburst
emission due to gravitational tidal interactions, most likely caused by
sub-cluster merging and other on-going processes of cluster virialisation.
