Born on 31 December 1813, the son of Honoratus Leigh Thomas, he was educated at the East India College at Haileybury. He went to India in 1832 as a writer in the Bengal service of the company. Poor health affected his career, and he took several absences in England on sick leave; and when Lord Dalhousie offered him in 1852 the post of foreign secretary to the government of India, he declined it.
After acting for a short time as judge at Delhi, Thomas was appointed superintending judge of the Saugor and Nerbudda territory. He retired on a pension in 1857, and spent the rest of his life in scholarly pursuits, attending the meetings of learned societies and writing on Asian archæology. He was elected a Fellow of the Royal Society in 1871, and appointed a Companion of the Order of the Indian Empire in the 1884 Birthday Honours.
Thomas is considered to have made ground-breaking studies in a number of areas of scholarship, such as numismatics (Bactrian, Indo-Scythic, and Sassanian coins); Indian metrology; and Persian gems and inscriptions. His work was recognised by his election as a Fellow of the Royal Society on 8 June 1871, as correspondent of the Institute of France in January 1873, and as honorary member of the Russian Academy; and by his decoration as Companion of the Indian Empire. His major works were:
Other publications included:
Many of his numerous short papers appeared in the Numismatic Chronicle between 1847 and 1883. Rather more were in the Journal of the Royal Asiatic Society, of which he was a member for 40 years and treasurer for 25.
Thomas is a common surname of English, Welsh, Scottish, French, German, Dutch, and Danish origin.
It derives from the medieval personal name, of Biblical origin, from Aramaic תאומא t'om'a, a byname meaning 'twin'. It was borne by one of the disciples of Christ, best known for his skepticism about Christ's resurrection (John 20:24–29). The th- spelling in English results from the initial letter of the name in the Greek New Testament being a theta. The English pronunciation as t rather than a dental fricative is the result of French influence from an early date. In Britain, the surname is widely distributed throughout the country, but especially common in Scotland, Cornwall, and Wales. Thomas is the ninth most common surname in the United Kingdom. It is found as a personal name among Christians in India, and in the United States; it is also used as a family name among the Saint Thomas Christian families from Kerala, South India.In the 1990 United States Census, Thomas was the twelfth most common surname, accounting for 0.3% of the population.In France, Thomas (pronounced [tɔma]) is the third most widespread surname after Martin and Bernard, with over 100,000 people with this name.