Degree (in %, first row) and angle (in degrees, second row) of polarisation as a function of position in the arc, from east to west, for the inner south-western arc (first column) and the outer south-western arc (second column), for all the observing bands (colour coded). Average value of the polarisation degree in a given band is indicated by the respective colour horizontal lines. Second row: the blue line corresponds to the expected polarisation position angle for these apertures if due to single scattering of light coming from the photo-centre of the AGN.