After attending the high school at Kirkcaldy, Andrew went to work for the Commercial Bank of Scotland.
Shortly after his twentieth birthday, he bought a sailing ship, the barque Willowbank, which he employed in the coasting trade.
During the First World War in March 1917 Weir was asked to report on the commercial organization of the supply branches of the army.
In January 1919, after the war had ended, he was appointed Minister of Munitions to close down the supply operation and dispose of unwanted materiel.
[citation needed] Inverforth continued to go to the office four days a week, into his ninety-first year.