Colonel Light was born at Kuala Kedah (Malaya) on 27 April 1786. His early years were spent in Theberton, Suffolk, England. He served at various times in both the Royal Navy and the British Army. He was in France in 1803 when war broke out and was interned by Napoleon at Verdun, but escaped after only one month. He visited India in 1805 and 1806 and returned to Europe in 1807. He left the Army in 1821 and, in 1823, he went to Spain to join an international volunteer force to aid the Spanish Revolutionary Army and was given the rank of Lieutenant Colonel. During an engagement at Corunna, Light was severely wounded and was desperately ill for some months. Eventually, he left Spain and returned to England in November 1823. He spent the next six years travelling Europe and the Mediterranean, accompanied by his second wife Mary Bennet. Between 1830 and 1835 he helped Mohammad Ali, founder of modern Egypt, to establish a Navy. Here Light met Rear Admiral Sir John Hindmarsh.
He arrived in South Australia in 1836, deciding upon the site for Adelaide on the last day of that year. His survey of Adelaide began on 11 January 1837, at what is now the junction of North and West Terraces, with the work being completed on 10 March. A granite obelisk marking the commencement of the survey is located on the northern side of the intersection. The naming of streets and squares took place on 23 May 1837.
Colonel Light resigned as Surveyor-General in June 1838, and died from tuberculosis on 6 October 1839. On 10 October he was buried in Light Square, Adelaide, and there is now a memorial over his grave in the form of a marble column.