[2] Veronica Jean Kathleen O’Neil was born on 11 March 1926 in Pontypridd, South Wales to Jennie K. and Gilbert O'Neil.
[4] When her husband and brother began studying for a Higher National Certificate in electrical engineering, Milligan joined them part-time whilst raising her children.
[2] When Milligan started a paid graduate traineeship at South Wales Electricity Board she became their first woman in engineering at the company.
[6] Milligan was appointed as a manpower advisor with the Department of Employment and Productivity,[6] later becoming a headquarters consultant providing expertise on the construction industry.
[2][11] She was awarded a bursary by the Caroline Haslett Memorial Trust to attend the First International Conference of Women Engineers and Scientists in 1964.
[2][17] Millgan grew up in Pontypridd, South Wales with her father, a school teacher, and brother Maitland O'Neil who was also an electrical engineer.