  CG J1720-67.8 is an ultra compact group of several galaxies with a low
velocity dispersion, and displaying the hallmarks of mutual interaction and
possible tidal dwarf galaxy formation. In hierarchical models, the system is a
possible precursor to a massive elliptical galaxy. In this paper, we use new
optical integral field spectroscopic and radio observations to investigate the
evolutionary status of the group in more detail: global star-formation rates
are estimated using H$\alpha$ and 1.4 GHz radio continuum measurements; H {\sc
i} observations provide an upper limit to the global neutral gas content;
optical broadband colours and spectra provide ages and stellar mass estimates
for the tidal dwarf candidates; the bidimensional H$\alpha$ velocity field is
used to trace the kinematics of the group and its members, which are compared
with numerical simulations of galaxy encounters. The observations suggest a
model in which multiple interactions have occurred, with the latest strong
encounter involving at least two major components within the last 200 Myr.
Debris from the encounter fuels ongoing star formation at the global level of
$\sim20$ M$_{\odot}$ yr$^{-1}$, with self-gravity within the tidal tail
possibly providing a mechanism to enhance the star formation rate of the tidal
dwarf candidates, with bursts of star-formation in clumps of mass $\sim2\times
10^7$ M$_{\odot}$ appearing within the last 10 Myr. The amount of time required
for final merging of all group components remains uncertain.
