  We revisit diffractive and exclusive W production at hadron colliders in
different models for soft colour exchanges. The process pp to p[WX]p, and in
particular a W charge asymmetry, has been suggested as a way to discriminate
diffractive processes as being due to pomeron exchange in Regge phenomenology
or QCD-based colour reconnection models. Our detailed analysis of the latter
models at LHC energies shows, however, that they give similar results as
pomeron models for very leading protons and central W production, including a
vanishing W charge asymmetry. We demonstrate that soft colour exchange models
provide a continuous transition from diffractive to inelastic processes and
thereby include the intrinsic asymmetry of inelastic interactions while being
at the same time sensitive to the underlying hadronisation models. Such
sensitivity also concerns the differential distributions in proton momentum and
W transverse momentum which opens possibilities to discriminate between
different colour reconnection models.
