From Wikipedia, the free encyclopedia. Mary Webster is a British actress best known for her 45 appearances as Sarah Onedin in the BBC nautical drama The Onedin Line (1971-79). Websters first television appearance was in The Man from the South for Cameo Theatre (1955). She went on to appear in, among others, A Christmas Carol (1958), William Tell (1958), The Moonstone (1959), Dixon of Dock Green (1963), Dr Finlays Casebook (1963), Redcap (1964), Danger Man (1965), The Troubleshooters (1966), Adam Adamant Lives! (1966), Jackanory (1968), Softly, Softly (1968), Z-Cars (1970), and The Onedin Line (1971-79). She appeared in the 1961 film Master of the World. Webster is married to William Slater, who directed several episodes of The Onedin Line. Description above from the Wikipedia article Mary Webster (actress), licensed under CC-BY-SA, full list of contributors on Wikipedia.