Diana Rigg was 25 in The Hothouse when she played the character 'Anita Fender'.
That was over 59 years ago in 1964.
This was her first recorded movie acting credit (although may not technically be her first actual acting role).
In 2020 she died aged 82, starring in 49 films in her career, 47 of those after The Hothouse was first released. If she were alive today she would be 85.
In The Hothouse, I think Diana Rigg looks: