Polarimetric data associated with multi-parameter observational campaigns of selected bright O-type stars and their variable winds, are analysed in relation to the outcomes of the UV and optical spectroscopic studies. For the stars {xi} Per and {lambda} Cep, individual measurement uncertainties are {Delta}p~+/-0.0002 with nightly mean uncertainties of {Delta}p~+/-0.00007. Although variability is apparent on a night-to-night basis, with differences in {Delta}p~0.0002, no correlations are found between these and the periodic behaviours associated with the stellar SiIV and H{alpha} lines.