Light backscattering by large randomly oriented particles of irregular shape is calculated using the physical optics approximation (PhOA). It is shown that the degree of linear polarization reveals the polarization surge because of the coherent backscattering. The sign of the polarization surge for pairs of conjugate beams can be either negative or positive depending on the shape of the photon trajectory that predominantly contributes to backscattering. Summing up the surges, we conclude that the conventional negative polarization phenomena are not obligatory in the case of a single backscattering particle.