[2][3] McHarg studied at the Glasgow High School for Girls and then at the University of Glasgow, earning a master's degree with first-class honours in mathematics and natural philosophy in 1943.
The university awarded her the Thomas Logan Medal and a George A. Clark scholarship, funding her as a researcher at Girton College, Cambridge.
[1] At Girton, she studied nonlinear partial differential equations with Mary Cartwright and completed her Ph.D. in 1948.
[1][4] McHarg returned to the University of Glasgow as a lecturer in 1948.
[1] She also translated the text Differential Equations by Francesco Tricomi from Italian into English; her translation was published in 1961 by Hafner and republished in 2012 by Dover Publications.