MacGregor was a Scot, born near Nairn, between Inverness and Aberdeen.
He emigrated to Canada in 1909 and joined the Canadian Forces in 1915. He enlisted as a private but was commissioned in the field later. He ended the war as a Captain, and saw service again in World War 2, ending that with the rank of Lieutenant-Colonel.
He was probably the most decorated soldier ever. He never forgot his Scottish heritage.