  The thermal reprocessing hypothesis in AGN, where EUV/X-ray photons are
reprocessed by the accretion disc into optical/UV photons, predicts
wavelength-dependent time delays between the optical continuum at different
wavelengths. Recent photometric monitoring by Sergeev et al. has shown that the
time-delay is observed in 14 AGN, and generally seen to increase with
increasing wavelength, as predicted in the reprocessing scenario. We fit the
observed time delays and optical spectral energy distribution using a disc
reprocessing model. The model delivers estimates for the nuclear reddening, the
product of black hole mass times accretion rate, and the distance to each
object. However, the distances at face value give H_0 = 44 +/- 5 km/s/Mpc - a
factor of 1.6 smaller than generally accepted. We discuss the implications of
this on the reprocessing model.

Astrophysics