  We develop a rapid algorithm for the evolution of stable, circular,
circumbinary discs suitable for parameter estimation and population synthesis
modelling. Our model includes disc mass and angular momentum changes, accretion
on to the binary stars, and binary orbital eccentricity pumping. We fit our
model to the post-asymptotic giant branch (post-AGB) circumbinary disc around
IRAS 08544-4431, finding reasonable agreement despite the simplicity of our
model. Our best-fitting disc has a mass of about $0.01\, \mathrm{M}_{\odot }$
and angular momentum $2.7\times 10^{52}\, \mathrm{g}\, \mathrm{cm}^{2}\,
\mathrm{s}^{-1}\simeq 9 \,\mathrm{M}_{\odot }\, \mathrm{km}\, \mathrm{s}^{-1}\,
\mathrm{au}$, corresponding to 0.0079 and 0.16 of the common-envelope mass and
angular momentum, respectively. The best-fitting disc viscosity is $\alpha
_\mathrm{disc} = 5 \times 10^{-3}$ and our tidal torque algorithm can be
constrained such that the inner edge of the disc $R_{\mathrm{in}}\sim 2a$. The
inner binary eccentricity reaches about 0.13 in our best-fitting model of IRAS
08544-4431, short of the observed 0.22. The circumbinary disc evaporates
quickly when the post-AGB star reaches a temperature of $\sim \! 6\times 10^4\,
\mathrm{K}$, suggesting that planetismals must form in the disc in about
$10^{4}\, \mathrm{yr}$ if secondary planet formation is to occur, while
accretion from the disc on to the stars at about 10 times the inner-edge
viscous rate can double the disc lifetime.
