She was by now a spinster approaching middle-age. She had very little of a social life since much of her spare time was spent looking after her ageing relatives, including her mother, aunt and uncle.
But in 1954, in a neighbouring office at the base, she became acquainted with Harry Houghton, a former sailor and now a civil servant. Houghton was a heavy drinker and his marriage close to collapse. He and Gee began an affair and she would pose as his wife while booking into hotels. However her commitment to her relatives meant that they could not marry for the time being.
In July 1960, Houghton introduced Gee to a man who she claims she only knew as "Alex Johnson" a commander from the United States Navy. "Johnson" wanted to know how the British were handling the information provided to them by the Americans.
By now Houghton and Gee were under surveillance by the British security service MI5. A Russian mole had warned Western intelligence about secrets being leaked from Portland, and Houghton's expenses, which went far beyond his salary, made him an obvious suspect.
MI5 identified "Johnson" as Gordon Lonsdale, a Canadian businessman.
Gee provided material to Houghton which he would photograph and deliver to Lonsdale in London. On the 6 January 1961 Gee left the base with pamphlets which included details of an ASDIC (sonar) device used for detecting submarines.
At first Gee protested her innocence. But during the trial, under questioning from the prosecution, she finally admitted that "In the light of what transpires now, I have done something terribly wrong, but at that time I did not think I had done anything criminal."