What age was Elizabeth Taylor when she was cast in her first starring role in "National Velvet"?

Dame Elizabeth Rosemond Taylor (27 February 1932 – 23 March 2011) was a British-born American actress, businesswoman, and humanitarian. She began her career as a child actress in the early 1940s, and was one of the most popular stars of classical Hollywood cinema in the 1950s. She continued her career successfully into the 1960s, and remained a well-known public figure for the rest of her life.

Taylor was cast in her first starring role at the age of 12, when she was chosen to play a girl who wants to compete in the exclusively male Grand National in National Velvet (1944). She later called it "the most exciting film" of her career. MGM had been looking for a suitable actress with a British accent and the ability to ride horses since 1937, and chose Taylor at the recommendation of White Cliffs director Clarence Brown, who knew she had the required skills. As she was deemed too short, filming was pushed back several months to allow her to grow; she spent the time practising riding. In developing her into a new star, MGM required her to wear braces to correct her teeth, and had two of her baby teeth pulled out.

National Velvet became a box-office success upon its release on Christmas 1944. Bosley Crowther of The New York Times stated that "her whole manner in this picture is one of refreshing grace", while James Agee of The Nation wrote that she "is rapturously beautiful... I hardly know or care whether she can act or not."