  In this paper we study the non-factorizable QED corrections to
W-pair-mediated (charged-current) four-fermion production in electron-positron
collisions. A brief account of the obtained analytical results is given. They
turn out to be different from the ones published in the literature. For the
first time numerical results are presented, in particular the effects on the W
line-shape. These effects are of the order of a per cent. Applying the same
methods to ZZ- or ZH-mediated four-fermion production, the non-factorizable
$O(\alpha)$ corrections to the Z or H line-shape vanish.
