British pre WW1 phaeton (Sunbeam?)

evtl_sunbeam_engl_postkarte_mystery

This phaeton could be a car from a British manufacturer, since the rear side of the photo is a postcard with English text.

The car bears a certain resemblance to Wolseleys, Napiers and Sunbeams from around 1910, but I did not manage to find a perfect match.

Any suggestions?