Lambert Cameron Jackson was educated at Clifton College, Bristol, and at the Royal Military Academy at Woolwich, London. He entered the British Army (Royal Engineers) in August 1895 with the rank of second lieutenant and was promoted to lieutenant in August 1898. During 1899 and 1900 he was employed on survey duty on the border between Sudan and Abyssinia (now Ethiopia). From 1900 to 1902 he served in the Anglo-Boer War and was awarded the Queen's Medal with 3 clasps. During 1903 and 1904 he served on the Anglo-German Yola-Chad [Nigeria-Chad] Boundary Commission and was promoted to Captain in August 1904.
In 1905 Jackson was sent to the Orange River Colony (now the Free State) in charge of the Colonial Survey Section, consisting of two officers of the Royal Engineers and four men, to conduct a topographical survey of the colony. He arrived in Bloemfontein in October. Using the existing geodetic stations as a basis the men carried out a secondary triangulation as well as a plane table survey of the whole territory. The work led to the compilation of the Topographical series of the Orange River Colony, on a scale of 1:125 000, of which 43 sheets were published between about 1907 and 1929. These remained the best maps of the territory for decades. Jackson remained in charge of the work until August 1908, when he was succeeded by H.J.L. Winterbotham*. That same year he was honoured as a Companion of the Order of St Michael and St George (CMG).
After serving as a general staff officer at the War Office from 1909 to 1911 Jackson was attached to the Army Staff College at Camberley, Surrey, to 1913. During World War I (1914-1918) he reached the rank of Major (October 1914) and brevet lieutenant-colonel (June 1916) and was awarded the Kings Medal with two clasps as well as the Distinguished Service Order (DSO). He subsequently served as general staff officer at the General Head Quarters of the British Army of the Rhine (1919), in Burma (now Myanmar, 1920), as assistant quartermaster-general at British Army Head Quarters in India (1920-1924), as deputy chief engineer of Eastern Command (1925-1928), as chief engineer of the British Army of the Rhine (1928-1929), and as chief engineer of Western Command (1930-1932). He retired in 1932, but served with the Home Guard during World War II (1939-1945). He was married to Olive Margaret Elphinstone, with whom he had two sons.