Belton, John (‘Johnnie’) Aloysius (1903–69), diplomat, was born 6 November 1903 at 37 Ballymahon St., Longford town, youngest child and second son of John Belton (b. 1861), corn and wool buyer, and his wife Margaret (b. 1867; née Farrell) who ran a stationery shop. He was educated at Blackrock College, Dublin, where he won many awards, including composition prizes in French and German. He then studied at UCD (BA (1924) MA (1926), LLB (1926)) and TCD (BL). Admitted to King's Inns (1924), he was called to the bar in 1927, and practised on the midland circuit (1927–9).
Belton joined the Department of External Affairs in 1929, among its first intake of third secretaries, then referred to as ‘cadets’, and was based in Dublin to 1933 attaining the rank of junior executive officer. He was posted to Paris in 1934 as secretary of the Irish legation. Returning to Dublin in 1937, he was promoted to assistant principal officer in 1939. When the Australian prime minister, Robert Menzies, visited Dublin in April 1941 it was Belton who acted as his guide. Menzies called Belton ‘Mr X’ in his 1967 memoirs Afternoon light, as Belton was then still serving in the Department of External Affairs. The two did not seem to hit it off, according to the Australian's account, with Menzies’ purposely overt deference to the British empire, and support for the British war effort, clashing with Belton's Irish nationalism and his support for Irish neutrality. Menzies acknowledged that it was he who came off worse in the encounter, being lashed by Belton's quick replies and acerbic turn of phrase.
Another promotion followed in 1941 when Belton was appointed counsellor at the Irish high commission in London. He became secretary of the high commission in 1943, but left London in 1945 as part of a general shake-up in the post-war Irish foreign service. After spending 1946 in Stockholm as chargé d'affaires en titre at this newly established Irish diplomatic mission, Belton was appointed envoy extraordinary and minister plenipotentiary to Spain in 1947, spending two years in Madrid. Following a United Nations decision to withdraw diplomats from the Spanish capital, Belton was instructed to remain in Madrid, with his Argentine counterpart; the two were the only foreign diplomats now resident in the city.
Belton returned to Dublin in 1949 to head temporarily the foreign trade division at External Affairs, before leaving for Bonn in 1950 as consul general to West Germany, with the personal rank of minister plenipotentiary. With an in-depth knowledge of Ireland's international trade relations, and with fluent German, Belton was considered by External Affairs to be an ideal choice as minister to West Germany. In 1951 he was appointed Ireland's first envoy extraordinary and minister plenipotentiary to West Germany. He spent four years in Germany, being awarded the Grand Cross of Service order by President Theodore Heuss for his services to developing Irish–German relations. He returned to Iveagh House as assistant secretary in 1955.
In 1959 Belton returned to Sweden, now as ambassador, his first posting at that rank. He was concurrently appointed ambassador to Norway. He was later to hold concurrent postings to Finland (1962) and Norway (1963). His last overseas posting was as ambassador to Canada (1964–7). He was considered by his colleagues as one of the best linguists in the service and had acquired the reputation of having opened more legations in his career than any other officer at the time. At the age of 64, and with one year left before reaching the statutory retirement age, Belton was appointed assistant secretary at External Affairs on 6 February 1967. He retired 6 November 1968, and died 19 September 1969 at a Dublin nursing home. He was buried in Deansgrange cemetery, Dublin on 22 September 1969.
He married Anne Frances O'Reilly (d. 1994); they had two sons, Eoin and Anthony. He left an estate of £9,344 to his widow.