The daughter of Brigadier Alan F. Thomson DSO, she married Major Sir Arthur Lindsay Grant, 11th Baronet, Grenadier Guards, in 1934.

She consistently polled at least 50% of the vote with the exception of her defeat in 1966, a feat never achieved by any succeeding candidates in the constituency.

She served as a Governor of the British Film Institute and a member of the general advisory council of the BBC.

[2] On 1 July 1970 she was created a life peer as Baroness Tweedsmuir of Belhelvie, of Potterton in the County of Aberdeen.

[citation needed] In 1983, the veteran Labour politician Emanuel Shinwell stated Tweedsmuir was 'the best' female MP Britain had had.