There was no doubt that Mrs. Cole was an inconveniently sharp woman. (HBP13)
Mrs. Cole was the matron of Tom Riddle’s orphanage. She was interviewed c. 1937 by Dumbledore and told him the circumstances of Tom’s birth and about his anti-social behavior (HBP13). Described as a “skinny, harassed-looking woman” with a “sharp-featured face that appeared more anxious than unkind” (HBP13). Harry judged Mrs. Cole to be inconveniently sharp, as she asked many questions of Dumbledore about himself, his school, and Tom Riddle. She also proves surprisingly adept at drinking gin, but retains her wits when she does so.
Holding her liquor (HBP13).
Other canon notes and references
Mrs. Cole describes Merope Gaunt as "not much older than myself" when she gave birth to Tom Riddle, aged 19 (HBP13). Since Merope was born in 1907, it can be inferred that Mrs. Cole was born around there as well; she had to be old enough to work in an orphanage by December 1926, so we can place her date of birth approximately between 1907 and 1909.