Hmm, so she was born 21st April, 1926. Her first decade was therefore 1926-1935, her second 1936-1945, her third 1946-1955, her fourth 1956-1965, her fifth 1966-1975, her sixth 1976-1985, her seventh 1986-1995, her eighth 1996-2005, and her ninth 2006-2015.
I'd have thought that even the proudly-innumerate arts graduates who write newspaper articles could have managed to get that right, given that from their studies of history they ought to know that the 1500s were the 16th century and that although we're in the 21st century right now the years start with 20.
I suppose their excuse would be that she did have some peaceful studies of her taken ten years ago after she had recently entered her tenth decade, but that's just trying to wriggle out of it...