Triple gauge boson couplings are measured from W-pair events recorded by the OPAL detector at LEP at centre-of-mass energies of 183 - 209 GeV with a total integrated luminosity of 680 pb-1. Only CP-conserving couplings are considered and SU(2) x U(1) relations are used, resulting in four independent couplings, and gz5. Determining each coupling in a separate fit, assuming the other couplings to take their Standard Model values, we obtain , gz1 = 0.987 + 0.034-0.033, and gz5 = -0.04 + 0.13-0.12, where the errors include both statistical and systematic uncertainties. Fits are also performed allowing some of the couplings to vary simultaneously. All results are consistent with the Standard Model predictions.