It is part of British sailing and forecasting folklore that the wind speed increases in the Dover Straits when there is an established wind-flow –westerly/south-westerly or easterly/north-easterly –along the English Channel. However the underlying mechanism of the phenomenon is unclear. We have used the Met Office ‘New Dynamics’ mesoscale model to perform a case study on an occasion when this phenomenon was observed in the Channel but not forecast well by the operational model, UM 4.5. Results are presented showing the sensitivity of forecasts to horizontal resolution (down to 2 km) and to vertical resolution. We probe the physical mechanism of the Channel jet by altering the surrounding orography and the land or sea surface roughness. Both the orography and the surface roughness are shown to influence the jet formation. Copyright © 2003 Royal Meteorological Society