1997. I don' know exactly when, nor do I know exactly how, however through my research I have found she died from a drug overdose.
Gary Oldman, who plays Sid in "Sid and Nancy" was given Sid's real necklace by Sid's mom. He wears it in the film too.
Sid Millward died in 1972.
Sid Dorfman died in 1988.
Sid Griffiths died in 1967.
Sid Colin died in 1989.
Sid Barron died in 2006.
Sid Barnes died in 1973.
Sid Russell died in 1994.
Sid Boyling died in 2006.
Sid Emery died in 1967.
Sid Tanenbaum died in 1986.
Sid Clewlow died in 1989.