ILR for ex army wives

[jamesmartin]

Hello all, i'm trying to find out some information whether my mother could have any form of indefinite leave to remain status. She is a German national who married my father, a British citizen, in the late 1970s. They are still married and living here in the UK. He was an army soldier at the time and served until mid 90s.

My mother seems to think she was given a stamp in her passport at the time but no longer has proof or the original document. We have looked into applying for permanent residence but she a) has not had CSI (but she has a NHS number) b) does not count as self sufficient as my father has supported them throughout the marriage (but has a NI number). She has never claimed benefits except for receiving child benefit.

Could anyone clarify immigration law from the 70s and if there was any differences for the armed forces?