Measurements of the event properties of hadronically decaying W bosons in W+W- events observed in the OPAL detector at LEP will be presented. Updated studies of inter-jet multiplicity based on the whole LEP2 data sample will be shown and compared with a variety of models of colour reconnection. Model dependent estimates of the fraction of reconnected events in data are made. These are used to estimate the size of the systematic uncertainty on M_w arising from possible Colour Reconnection effects.