"Red Joan is based on a novel of the same name written by Jennie Rooney, which was itself inspired by the life of Melita Norwood.[3] Norwood worked at the British Non-Ferrous Metals Research Association as a secretary and supplied the Soviet Union with nuclear secrets." Wikipedia.
You can watch it using the video Hoopla streaming service, from your local library.
And here, I thought it was just the Rosenbergs that leaked nuclear secrets. No wonder McCarthyism took off with all these leaks from average citizens. The government would start questioning everyone. Obviously, they went overboard but this kind of thing probably gave it impetus.