Patricia Marmont (wiki), American-born British Hollywood actress, won't be celebrating her 100th in August as she died on 3rd December 2020 aged 99 according to this Ancestry family tree.
It says she died at Denville Hall, likely credible as it matches info in this Facebook post from February 2019 where someone says they went to visit her there.
Biggest role was as Andromache in the 1956 Warner Bros. epic Helen of Troy. Last film role was in a 2004 British film. Married for a period to character actor Nigel Green (1924–1972, wiki)