Sally Thomsett (born 3 April 1950 in Sussex, England) is a British actress.
She is mainly remembered for starring in the 1970 film The Railway Children and for playing Jo in the TV sitcom, Man About The House (1973-1976). She also appeared in the 1971 movie Straw Dogs, where she played an attractive girl accidentally killed by the mentally handicapped character.
In 1970 Thomsett was cast as the 11-year old Phyllis, despite the actress being 20 years old at the time. Her contract forbade her to reveal her true age during the making of the film and was also not allowed to be seen smoking or drinking during the shoot. After release, she received a BAFTA award nomination for Best Promising Newcomer.
She is married to Paul Agnew, a landscape gardener, and they have one child.