He was the son of Edith (née Nelson) and Sir William Haldane, grandson of James Alexander Haldane, and nephew of Richard Burdon Haldane, 1st Viscount Haldane. His brother was Graeme Haldane and he married Janet Macrae Simpson-Smith.
Like his father and uncles, he attended the Edinburgh Academy, after which he went up to Balliol College, Oxford to read history. He returned to Scotland to enter his father's legal firm and acted for a time as Fiscal to the Society of Writers to the Signet. He then became involved in the Savings Bank movement and was at one stage vice-chairman of the Savings Bank Association. In 1982, he was awarded the CBE in recognition of his work for the bank.
He was principally known, however, as a social historian and author, and for his seminal work on the drovers' roads of Scotland. In recognition for his work in this field, he was awarded the honorary degree of D Litt from the University of Edinburgh. He published two further books in this field, New Ways through the Glens and Three centuries of Scottish posts, as well as several on his favourite pastime of trout fishing, of which he was passionately fond.