Thea King was born in Hitchin, Hertfordshire, the daughter of Henry Walter Mayer King, the manager of his family engineering business, and Dorothea (née Hass).[1] She was educated at Bedford High School and won a scholarship to the Royal College of Music where she studied the piano with Arthur Alexander and the clarinet with Frederick Thurston.[2] In January 1953 she married Frederick Thurston but he died from lung cancer in December of the same year. She never remarried.[1]
Thea King made a special study of lesser known works of the 18th and 19th centuries, especially those of Crusell.[2] She commissioned Elizabeth Maconchy's Fantasia and Howard Blake's Clarinet Concerto.[1] Compositions dedicated to her by British composers include Benjamin Frankel's Clarinet Quintet (which she recorded in 1991, helping revive interest in the then neglected composer)[3] and Gordon Jacob's Mini Concerto.[2]
From 1961 to 1987, she was Professor of Clarinet at the Royal College of Music and she was a professor at the Guildhall School of Music and Drama from 1988 until her death. She was a Fellow of both institutions.
Thea King was made an OBE in 1985 and was appointed a DBE in 2001.[2]