The Standard Model prescribes a definite Lagrangian for the coupling o
f the W-boson to the photon. Measuring the coupling constant will test
an important ingredient of the Model i.e., the verification of non-Ab
elian gauge structure of the Standard Model. Using the process e gamma
--> W nu we study the most general C and P conserving vertex in e(+)e
(-) collisions at a future 500 GeV collider. This vertex contains two
parameters, the anomalous magnetic moment kappa and the quadrupole mom
ent lambda. For the process e gamma --> W nu we present analytical exp
ressions for the differential cross-section for arbitrary values of ka
ppa and lambda which explicitly demonstrate the presence of a zero at
u = 0 in the Standard Model.