  The methods of calibrating the luminosities of galactic Cepheids and
determining Cepheid reddenings are considered in some detail. Together with
work on NGC4258 this suggests that the calibration presented is valid to about
0.1mag (s.e.) at least for Cepheids with near-solar abundances. Metallicity
effects are considered, partly through the use of non-Cepheid moduli of the
LMC. To reduce the uncertainty substantially below 0.1mag will require
extensive work on metallicity effects. Non-linearities in the period-luminosity
and period-colour relations will also need to be considered as will the need to
distinguish unambiguously between fundamental and overtone pulsators.
