  We are engaged in a wide-field, multi-colour imaging survey of X-ray selected
clusters at intermediate and high redshift. We present blue fractions for the
first 8 out of 29 clusters, covering almost a factor of 100 in X-ray
luminosity. We find no correlation of blue fraction with redshift or X-ray
luminosity. The lack of a correlation with L$_{X}$, places strong constraints
on the importance of ram-pressure stripping as a driver of the Butcher-Oemler
effect.
