Aird was the second son of Malcolm Aird (1899–1965), who was a grandson of Sir John Aird, 1st Baronet, and his wife Joan née Sturgis. He was educated at Eton and the Royal Military Academy Sandhurst and joined The 9th Queen's Royal Lancers as a Captain in 1951.
From 1960 to 1964, he was a Temporary Equerry to the Queen Mother and then her Assistant Private Secretary and Extra Equerry from 1964 to 1973, Comptroller from 1974 to 2002 and Private Secretary and Equerry from 1993 to 2002. After Queen Elizabeth's death in 2002, Sir Alastair was made an Extra Equerry to The Queen in 2003.
On 22 July 1963, he married Fiona Myddelton, LVO who was an Extra Lady-in-Waiting to Princess Margaret from 1960 to 2002. The couple lived in Dorset and had two daughters. The elder, Caroline, is a god-child of Princess Margaret. 
- Obituary, Daily Telegraph, 1 October 2009
- Sir Alastair Aird - Daily Telegraph obituary