& 6742.3 & times.\

The evolution of clustering with cosmic time is widely recognised as one of the most rigid tests of the cold dark matter paradigm [@Kaiser91; @Springel05]. However, locating high redshift clusters is challenging. The traditional methods of X-ray and blind optical searches are limited: X-ray surveys can detect only the most luminous sources at high-$z$, while optical searches are highly vulnerable to projection effects. In order to overcome these limitations, a way of targeting the search is needed.

Since the earliest studies, it has been established that quasars are associated with groups and clusters of galaxies [@Bahcall69; @Oemler72]. More recently, @McLure01 argued that a close match between the space density of clusters and that of quasars indicates that practically all clusters contained an AGN at high redshift. Further, @Rawlings04 propose that radio jets from AGN are a major influence on cluster evolution. They suggest that a galaxy merger within the cluster triggers a radio-jet episode; the jets then delivery energy to the intracluster medium, heating it and preventing it from falling into the other developing cluster galaxies. These galaxies are thus starved of fuel, and star formation within the cluster will effectively shut down. @Rawlings04 speculate that 