  Accurate methods for reverberation mapping using photometry are highly sought
after since they are inherently less resource intensive than spectroscopic
techniques. However, the effectiveness of photometric reverberation mapping for
estimating black hole masses is sparsely investigated at redshifts higher than
$z\approx0.04$. Furthermore, photometric methods frequently assume a Damped
Random Walk (DRW) model, which may not be universally applicable. We perform
photometric reverberation mapping using the Javelin photometric DRW model for
the QSO SDSSJ144645.44+625304.0 at z=0.351 and estimate the H$\beta$ lag of
$65^{+6}_{-1}$ days and black-hole mass of
$10^{8.22^{+0.13}_{-0.15}}M_{\odot}$. An analysis of the reliability of
photometric reverberation mapping, conducted using many thousands of simulated
CARMA process light-curves, shows that we can recover the input lag to within 6
per cent on average given our target's observed signal-to-noise of > 20 and an
average cadence of 14 days (even when DRW is not applicable). Furthermore, we
use our suite of simulated light curves to deconvolve aliases and artefacts
from our QSO's posterior probability distribution, increasing the
signal-to-noise on the lag by a factor of $\sim2.2$. We exceed the
signal-to-noise of the Sloan Digital Sky Survey Reverberation Mapping Project
(SDSS-RM) campaign with a quarter of the observing time per object, resulting
in a $\sim200$ per cent increase in SNR efficiency over SDSS-RM.
