'12 O'Clock High'
"Then Came The Mighty Hunter"
Because of other Toobworldly factors, I believe this episode took place in the latter half of 1944. If so, then the movie in question was probably "His Butler's Sister".
"His Butler's Sister" was released in America in November of 1943. It didn't premiere in Sweden until May of 1944. (UK premiere information was not available at the IMDb.) Her other two films in 1943 premiered overseas in that same year and that would be too soon for this episode to still be playing and Gillian never got around to seeing it.
Her next film, "Christmas Holiday" would not have premiered in Europe until 1945 and that would have been too late.
So Toobworld is going to fill in the blanks by claiming it was "His Butler's Sister" which also starred Franchot Tone, Pat O'Brien, Akim Tamiroff, Alan Mowbray, and Hans Conreid among others.
Deanna Durbin would have been 93 years old today.....