Duncan Forbes was born on 10 November 1685, in Culloden House, near Inverness, second son of Duncan Forbes, 3rd laird of Culloden, and Mary Innes. His elder brother, John (1673-1734) was 12 years older. Forbes attended the local grammar school and then matriculated at Marischal College in Aberdeen in 1699. His brother John inherited the Culloden Estate when their father died in 1704. Forbes briefly attended the University of Edinburgh in 1705, then received his law degree from Leyden University in the Netherlands. He returned to Scotland in 1707 and in married Mary Rose in 1708. They had one surviving child, John Forbes (1710-1772.) Upon his brother John’s death in 1734, Forbes inherited the Culloden Estate as the 5th laird.

During the Jacobite Rising of 1715, Forbes and his brother raised independent companies and fortified Culloden and Kilvarock. They joined forces with Simon Fraser, Lord Lovat, and forced Inverness to surrender to them just before the Jacobite defeat at the Battle of Sheriffmuir. As a reward, Forbes was made Depute-Advocate in March 1716. This required him to prosecute Jacobite prisoners being held in Carlisle, contrary to the accepted practice they be tried in the counties where the actions were alleged to have taken place. Forbes regarded this as unjust and apparently collected money for the support of Scottish prisoners in Carlisle.

In 1721, Forbes represented Ayr Burghs as a Member of Parliament (MP.) Then in 1722, he was elected for Inverness Burghs, a seat he held until 1737 when he resigned. Forbes was appointed as Lord President of the Court of Session, becoming the senior legal officer in Scotland. He held this position until his death in 1747.

The 1745 Jacobite Uprising began when Prince Charles and a few companions landed on Eriskay on 23 July. Forbes received word of the landing on 9 August and he notified the British Government in London. After the Jacobite army entered Edinburgh and achieved a victory at Prestonpans in September, Forbes and John Campbell, Earl of Loudoun based themselves in Inverness with around 2,000 recruits. They were forced to retreat to the Isle of Skye when the Jacobites retreated to Inverness after abandoning the siege of Stirling Castle in February 1746. Prince Charles used the Culloden Estate as his headquarters during the preparations for the Battle of Culloden. After the British Government victory in Culloden in April, Forbes returned home to find his house looted and all his cattle stolen.

While he supported severe penalties for the leaders, Forbes counselled that 'Unnecessary Severitys create Pity.' He opposed the 1746 Dress Act banning Highland attire except when worn in military service, arguing it was unnecessary and enforcement of the 1716 Disarming Act was more important. This advice was largely ignored.

Forbes himself was financially ruined by the Rising, due to the damage done to his estate and because he was never reimbursed for the monies spent on behalf of the government. He died on 10 December 1747 and was buried in Greyfriars Kirkyard, near to his brother John. A statue of him by Louis-François Roubiliac was erected in the Parliament House, Edinburgh by the Faculty of Advocates in 1752.

Left, top: The Honourable Duncan Forbes of Culloden Lord President of the Court of Sessions, To the Right Honourable Phillip Lord Hardwick Lord Chancellor of Great Britain.

Left, bottom: Statue of the Honourable Duncan Forbes of Culloden Lord President of the Court of Sessions by Louis-François Roubiliac was erected in the Parliament House, Edinburgh.