  We study the mutual evolution of the orbital properties of high mass ratio,
circular, co-planar binaries and their surrounding discs, using 3D Smoothed
Particle Hydrodynamics simulations. We investigate the evolution of binary and
disc eccentricity, cavity structure and the formation of orbiting azimuthal
over-dense features in the disc. Even with circular initial conditions, all
discs with mass ratios $q>0.05$ develop eccentricity. We find that disc
eccentricity grows abruptly after a relatively long time-scale ($\sim
400\textrm{--}700$ binary orbits), and is associated with a very small increase
in the binary eccentricity. When disc eccentricity grows, the cavity semi-major
axis reaches values $a_{\rm cav}\approx 3.5\, a_{\rm bin}$. We also find that
the disc eccentricity correlates linearly with the cavity size. Viscosity and
orbit crossing, appear to be responsible for halting the disc eccentricity
growth -- eccentricity at the cavity edge in the range $e_{\rm cav}\sim
0.05\textrm{--} 0.35$. Our analysis shows that the current theoretical
framework cannot fully explain the origin of these evolutionary features when
the binary is almost circular ($e_{\rm bin}\lesssim 0.01$); we speculate about
alternative explanations. As previously observed, we find that the disc
develops an azimuthal over-dense feature in Keplerian motion at the edge of the
cavity. A low contrast over-density still co-moves with the flow after 2000
binary orbits; such an over-density can in principle cause significant dust
trapping, with important consequences for protoplanetary disc observations.
