MacArthur began acting with the amateur Ardrossan & Saltcoats Players. She made her London stage debut that year, in
Alec Coppel's
The Gazebo, at the
Savoy. With the
Royal Shakespeare Company in the 1960s, she played Lady Montague in
Romeo and Juliet. She was twice in London productions of
The Prime of Miss Jean Brodie, in different roles, in 1966 and in 1994–1995. She was long associated with the
Pitlochry Festival Theatre. MacArthur was frequently seen on television, with a long list of credits including
Z-Cars,
The Borderers,
The Troubleshooters, ''
Sutherland's Law, The Standard, The Omega Factor, The Sandbaggers, Doctor Finlay, Hamish Macbeth, Casualty and Sea of Souls. In 1972, she played the tragic Scottish mother Jean Guthrie in Sunset Song'', the television adaptation of
Lewis Grassic Gibbon's novel. Her best-known role was the Lady
Laird Elizabeth Cunningham in
Take the High Road, MacArthur was said to have discovered the future
Doctor Who actor
David Tennant. After seeing his first performance at age 10 in
Paisley, she told his parents he would become a successful stage actor. Tennant went on to play MacArthur's son twice on stage, in ''
Long Day's Journey into Night and Hay Fever''. == Personal life ==