Born in Guildford, Surrey, England. Longtime assistant to Alfred Hitchcock, she was hired to be a secretary in 1933 and soon graduated to reading books and scripts and writing synopses. She accompanied the Hitchcocks to Hollywood and began collaborating on the screenplays of several of his notable films. She was hired as a scriptwriter by MGM in 1941, and in 1943 she became a producer at Universal. From 1955 to 1961, she produced the TV series "Alfred Hitchcock Presents," and she was producer of "The Alfred Hitchcock Hour" from 1962 to 1964. Harrison's writing credits, alone or in collaboration, include REBECCA and FOREIGN CORRESPONDENT (both 1940), SUSPICION (1941), SABOTEUR (1942), DARK WATERS (1944), NOCTURNE (1946, also producer), RIDE THE PINK HORSE (1947, uncredited, also producer), and YOUR WITNESS (1950, uncredited, also producer). Her other feature producer credits include THE STRANGE AFFAIR OF UNCLE HARRY (1945), THEY WON'T BELIEVE ME (1947), ONCE MORE, MY DARLING (1949), and CIRCLE OF DANGER (1951). As executive producer at Universal, she was responsible for JOURNEY TO MIDNIGHT and JOURNEY INTO DARKNESS (both 1968), and JOURNEY TO MURDER (1971). Married to novelist/screenwriter Eric Ambler from 1958 until her death in 1994.  Nominated for Writing (Screenplay) 1940: REBECCA (w. Robert E. Sherwood)  Nominated for Writing (Original Screenplay) 1940: FOREIGN CORRESPONDENT (w. Charles Bennett) 2 nominations