He was born in Lanark the eldest son of William Elliot, of the livestock auctioneers' firm Lawrie and Symington, and his wife, Ellen Elizabeth Shiels.

In the election for Rector of the University of Glasgow in 1908, Elliot assisted the Liberal Club campaign to elect the Liberal David Lloyd George, supported the candidacy of George Curzon, 1st Marquess Curzon of Kedleston, and according to Henry Mavor, ultimately voted for Keir Hardie, founder of the Labour Party.

[2] After the war, Elliot refused his father's urging to enter the family business, Lawrie and Symington, and instead began a political career after being asked to stand for election while recovering from his war-wound.

[2] During his first stint in parliament he shared a house in Westminster with Liberal MP Colin Coote, who was later to write a biography of Elliot.

[2] He briefly lost the post during the Labour Party's 1924 first MacDonald ministry, but regained it after Baldwin's return to power that same year.

[2] He was involved in the passage of the Local Government Act 1929, as well as reforms to administration in Scotland in 1928 and changes to Scottish ministers' positions in 1926.

His proposers were Sir Robert Blyth Greig, Frederick Orpen Bower, Arthur Crichton Mitchell, and William Archer Porter Tait.

[1] Elliot was involved in the Empire Marketing Board from October 1927, having been appointed president of the Imperial Research Conference in Westminster Hall.

[2] In May 1928, Elliot and Arthur Samuel, the Financial Secretary to the Treasury were reported to be working together in helping the Chancellor of the Exchequer, Winston Churchill in the budget debate.

While Minister of Agriculture, Elliot asked John Boyd Orr, who advocated a national food policy, to prepare a report on nutrition and public health, though it went unpublished because of their political ramifications.

[6] Orr published the report himself as Food, Health and Income in early 1936, advocating national and international co-ordination on nutrition.

Consequently, his political stock began to fall and when Winston Churchill replaced Neville Chamberlain as Prime Minister in 1940, Elliot was dropped from the government.

[2] After refusing the governorship of Burma, in January the following year he accepted the role of director of public relations at the War Office.

[2] In May 1941, during the London Blitz, Elliot chanced to be nearby the Palace of Westminster during a heavy air-raid which damaged the building.

[2] At the end of the year Elliot left his job at the War Office; he retired from the British Army having been promoted colonel.

[2] In the beginning of 1943, Elliot suffered serious injury in an accident at the railway station at Hawick, while boarding a train on the Waverley Route between Edinburgh and Carlisle.

[2] In this time he was chair of committee on herring fisheries and published a collection of broadcasts he had made the previous year as Long Distance.

[2] Elliot had a meeting with Joseph Stalin as part of a parliamentary delegation to the Soviet Union, one of the Allies, in spring 1945.

[2] In the 1945 general election which brought the Attlee ministry to power, he lost the Glasgow Kelvingrove constituency to Labour's John Williams[2] by just 88 votes.

When the university seats were abolished, Elliot returned to Kelvingrove where he beat his Labour opponent from 1945, John Lloyd Williams, and SNP candidate Hugh MacDiarmid in the 1950 election.

[11] The same year, Elliot undertook a journey to the newly established State of Israel to report for The Daily Telegraph.

[2][12] Elliot married Helen Hamilton on 27 August 1919, but she died on 8 September in a mountaineering accident on their honeymoon on the Isle of Skye's Cuillin hills.