Born in London, Stranks was ten years old when she played the role of the younger Emmeline Foster in the romantic adventure film The Blue Lagoon (1949).
She then played Janet Smith, the young sister of Ann Todd, in the David Lean film Madeleine (1950).
Stranks played a young student in the crime drama Sapphire (1959), and had a small part as a schoolgirl in the train scenes of The 39 Steps (also 1959) starring Kenneth More.
She was a regular panellist on the TV pop music show Juke Box Jury, and also appeared in Emergency Ward 10.
Following Magpie, Stranks devised and presented a programme for pre-school children, named Paperplay, which ran until 1981.