This death may have been reflected in recent Debrett's but I do not find it recorded here.
GEORGIANA BUTLER Obituary
Published by Ottawa Citizen on Aug. 26, 2015.
BUTLER, Georgiana Mary
1928 - 2015
Georgiana Mary Butler (née North) died while swimming at her favourite lake, an activity she loved... The daughter of Muriel North and the Honourable John North, she grew up with her mother in Norfolk, England...
As a young woman, she moved to London where she met her future husband, Esmond Unwin Butler. Shortly after marrying, they moved to Ottawa where Esmond took up his position as Secretary to five consecutive Governors General starting with General Vanier. At Rideau Hall, Georgiana served as Lady-in-Waiting, a role she filled with competence and dedication. In 1986, Esmond became Ambassador to Morocco, a country Georgiana loved exploring and learning about...
Georgiana is survived by her brother, Sir Jonathan North and sister Dr. Serena Colchester; son Mark (Gretchen) and daughter Clare; and grandchildren Abush Dapore Mills and seven month old Lucy Georgiana Catherine.
https://www.legacy.com/us/obituaries/legacyremembers/georgiana-butler-obituary?id=43026986Her brother died in 2018:
https://groups.google.com/g/peerage-news/c/XJIX8dQ3yUw/m/grMwjHG5DgAJGeorgiana Mary North Butler
Birth
1928
England
Death
Aug 2015 (aged 86–87)
Ottawa Municipality, Ontario, Canada
Burial
Beechwood Cemetery
Ottawa, Ottawa Municipality, Ontario, Canada
https://www.findagrave.com/memorial/291646846/georgiana-mary-butlerHer husband is in the same cemetery:
Esmond Unwin Butler
Birth
13 Jul 1922
Manitoba, Canada
Death
18 Dec 1989 (aged 67)
Canada
Burial
Beechwood Cemetery
Ottawa, Ottawa Municipality, Ontario, Canada
She was granddaughter of the 8th Earl of Guilford and also of Sir William Norton Hicking, Bt. (whose Baronetcy went by special remainder to Georgiana's brother).