A feather in his cap ! . Sean Upping starts on the Thames . The King ' s swan master and representatives of the Dyers and Vintners Companies left Vintry Wharf , Southwark Bridge for the annual task of swan upping . All Thames swans belong either to the Crown or the Dyers and Vintners Companies . Swan upping means that young birds are marked on the beak to show the owner . Photo shows , Mr R H Turk , the Vintners ! Company swan marker with a feather in his cap as he left Vintry Wharf . 20 July 1936 .