Nixon was a talented British animal illustrator noted for an orientalist approach and sharp clarity to the subject, reminiscent of Japanese woodblock prints. She lived in India for 25 years, where she illustrated for the Time of India Press, designed 30 nature posters for the Indian State Railways, painted horse portraits and a mural of wild ducks for the Bombay Natural History Museum. After returning to England, she wrote and illustrated numerous children's animal stories and painted animal portraits. Kay's best know illustration is Brer Rabbit and furry farmyard friends.

She also skilfully characterises pandas, elephants, lions and snakes. She was the recipient of many awards and medals and made an 'Academic of Italy with Gold Medal' in 1980.

She exhibited in 1920-26 in Birmingham and Coventry. She studied at the Camden and Birmingham Schools of Art. Back in England she illustrated Maurice Burton's bird families (London 1962).

She illustrated in 40 books , five of which she wrote herself.  See below:

1. Animal Legends
2. Pushti(Siamese Kitten)
3. Animals and Birds Folklore
4. Pindi Poo
5. Animal Mothers and Babies
6. Strange Animal Friendships
7. The Bushy Tail Family.
8. Whispers of the Wilderness (Batten H Mortimer)
9. Tales of Wildlife in Canadian Forests.
10. Kay also designed the interior for a maharajah's private aircraft.