lexander Beatson was the second son of Robert Beatson, of Kilrie in Fife. He joined the Army as a Cadet in 1775, and became an Ensign in the Madras Infantry in November 1776, serving as an Engineer in the war against Haidar Ali. In Cornwallis's campaigns of the Third Mysore War, he was Captain of Guides, and made many maps and sketches of the Baramahal. He probably met Devis in Madras in 1793. The artist, whose studio was in Calcutta, had travelled South to make studies (for a large group portrait), of individuals who had fought in the recent war (1790-92). In the Fourth Mysore War, Beatson served as a Major, and led the advance round the Southern rampart. He was later appointed Surveyor-General.

Beatson published his 'View of the Origin and Conduct of the War with the late Tippoo Sultaun' in May 1800, exactly twelve months after the fall of Seringapatam. In his Introduction, Beatson acknowledges the aid and patronage given to him by the Marquis Wellesley. He explains:

'Upon the disclosure of Tippoo Sultaun's hostile designs, his Lordship transmitted to the Government of Fort St.George, certain queries relative to military operation in Mysore; and directed, that the answers should be sent to him by an officer capable of affording such further information as he might require. It was my peculiar good fortune to be employed on this occasion. I was then engaged in an investigation and survey in the Northern Circars; and upon receiving an express from the Government of Madras, I repaired to Calcutta with all possible expedition. After remaining a few weeks with the Governor-general, he was pleased to honour me with the appointment of Aid-de-camp; to which, when it became necessary to declare war against Tippoo Sultaun, he added that of Surveyor General to the Army in the Field.

The campaign terminated with the capture of Seringapatam. There was no prospect of further field service; and finding my health impaired, I was compelled to quit a situation no less flattering than agreeable.'

From 1808 - 1813, Beatson was Governor of St Helena, promoted to the rank of Lt.General in 1814. He returned to England, and became interested in agriculture, farming at Knole Farm, near Tunbridge Wells, and at Henley, in Essex. He died on 14th July 1833.