he blazar emission - attributed to incoherent synchrotron processes involving relativistic electrons - is expected to be highly polarised especially in the optical bands. The specific conditions required for the emergence of polarisation, the emission and radiative transfer processes subsequently make the polarisation parameters and their dynamics, unique probes of the microphysics of the emitting plasma as well as the conditions and the configuration of the magnetic field at the emission site. The recent discovery of rotations of the polarisation angle seen associated with high energy flares observed in the GeV energy bands, opened up a new field dealing with the nature of the emission and variability mechanisms, the configuration of the magnetic field and high energy emission site etc. The degree of difficulty involved, has limited the polarisation studies - and especially monitoring - to hand-picked cases rather than unbiased samples forbidding systematic population studies. In order to lay the ground for systematic and extensive polarimetric studies we have concieved, designed and constructed a novel-design optical polarimeter that has already been commissioned at the Skinakas telescope in Crete. The program aims at monitoring the linear polarisation for a sample of almost 100 gamma-ray loud sources that comprise an unbiased set and 15 gamma-ray quiet "comparison sample sources'' with a duty cycle of close to 3 days for non active sources and for a fraction of a night for cases in active state. The achieved precision in the polarisation degree reaches a fraction of the percentage for sources of 18-th magnitude.  Here we present: (a) the scientific motivation, (b) the design of the instrument, (c) the sample selection and (d) the results from the first season of operation. We show that while the fractional polarisation for both gamma-ray--loud and gamma-ray--quiet sources are well-described by exponential distributions, the two classes have different optical polarisation properties.  This is the first time this statistical difference is demonstrated in optical wavelengths.