Hooper, from Ryde on the Isle of Wight, became UK's oldest person on Thursday following the death of Ethel Lang, who was 114.
Hooper is the UK's most senior super-centenarian according to the Gerontology Research Group records.
On learning of her achievement, she said: "I am surprised, I thought I was just the oldest person on the island."
Hooper, who has four grandchildren and six great grandchildren, was born in the same year as the Wright brothers invented the first aeroplane.
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"I have always lived a straight life, never done stupid things. I have never gone beyond the limit, always been active. I think always being active keeps you young.
"I have done what I wanted to do and helped others as much as I could.
"I do not feel anything like the age I am, I do not feel any different to when I was 70," she said.
She was brought up in Rottingdean, east Sussex and went on to become a concert pianist before starting a car hire business in the 1920s.
She later ran Kingscliff House School, which is now Brighton College.
After being widowed in 1977 she moved to the Isle of Wight two years later to be near her son, an 84-year-old retired pilot.
Members of her family travelled from across the UK and as far away as British Columbia to be with Gladys for her big day.