properties of a well defined large sample of bright QSOs at $z\le 0.3$, and provide key information on the following issues: [*what is the typical mass of DMHs hosting AGN? What is the typical bias factor for AGN? What is the duty cycle for AGN activity? What is the typical efficiency of the central engine at the various redshifts?*]{}

The plan of the paper is as follows. In § 2 we describe the data used in the statistical analysis. The various techniques used to investigate the clustering properties are presented in § 3, while § 4 is devoted to a comparison with similar results obtained by previous surveys at low redshifts. To investigate the redshift evolution of the clustering, the spatial properties of QSOs in the local universe are compared in § 5 to the recent 2QZ results at intermediate redshifts for QSOs and to various estimates for normal and peculiar galaxies. In § 6 physically motivated models are used to link the galactic structures at high-$z$ with the local AGN and galaxy population. In § 7 we discuss the clustering properties of QSOs in the light of these simple theoretical models. Finally § 8 gives some concluding remarks on 