  We have monitored the R-band optical linear polarisation of ten jetted NLSy1
galaxies with the aim to quantify their variability and search for candidate
long rotation of the polarisation plane. In all cases for which adequate
datasets are available we observe significant variability of both the
polarisation fraction and angle. In the best-sampled cases we identify
candidate long rotations of the polarisation plane. We present an approach that
assesses the probability that the observed phenomenology is the result of pure
noise. We conclude that although this possibility cannot be excluded it is much
more likely that the EVPA undergoes an intrinsic evolution. We compute the most
probable parameters of the intrinsic event which forecasts events consistent
with the observations. In one case we find that the EVPA shows a preferred
direction which, however, does not imply any dominance of a toroidal or
poloidal component of the magnetic field at those scales.
