Born Margaret Grundy in Wallsend, England, Cotton was the last surviving of 14 siblings, Necaise said.
She moved with her family to Dunedin when she was 4, then to Lower Hutt when she was older.
As a young woman, she worked at a munitions factory in Lower Hutt, packing explosives to support the troops during World War 2.
It was there she met her future husband, the late Roy Cotton, who worked as a supervisor. They married in September 1945.
The couple had one child and adopted another.
Cotton later worked at Griffins, making Christmas cookies.
The Cottons moved to Dunedin in the late 1970s.
The family would regularly travel to Hawaii for Thanksgiving, where they visited relatives and made a family tradition of taking a picture with Santa.
Cotton was 98 when she last visited Hawaii, Necaise said.
She hoped her mother would get to visit again.
Cotton has seven grandchildren and many great-grandchildren and great-great-grandchildren. Two more are on the way.
Some friends had an afternoon tea yesterday to mark the special occasion and the family, including all of Cotton's nieces and nephews, will attend a dinner on Saturday.