John Bramston was born at Roxwell, Essex, England, the second son of Thomas William Bramston, who represented South Essex in the House of Commons in 1835-65, and his wife Eliza, daughter of Admiral Sir Eliab Harvey who commanded the Temeraire at Trafalgar. He was educated at Winchester and Balliol College, Oxford. He then studied law while his scholastic attainments were recognized by his election as a fellow of All Souls. He entered the Middle Temple and was admitted to the Bar in 1857.

John Bramston met his companion, Robert Herbert , in the early 1850s at Balliol College, Oxford University, England. The pair shared rooms at Oxford, and also in London. When Herbert was Premier of Queensland, and Bramston his Attorney-General, the two created a farm on what is now the site of the Royal Brisbane and Women's Hospital. They named the farmhouse in which they both lived "Herston", a combination of their names. It also became the name of the modern-day Brisbane suburb of Herston, in the same location. They lived openly together, despite the fact that sodomy was punishable by death until 1864.

Bramston entered Queensland's Legislative Council in July 1863, serving in Herbert's ministry to February 1866. He was a minister without portfolio, except in August-September 1865 when he was attorney-general. He made few direct contributions, and attended only two of the six meetings of cabinet whilst attorney-general. In 1867 he went to England where he probably intended to remain, since he accepted office as assistant boundary commissioner for Devon and Cornwall.

He was responsible for such measures as the Common Law Process Act, the amended Marriage Act and the Insolvency Act. Never popular, when he left the Legislative Council to stand for the assembly he was defeated three times. His candidature was 'hawked about the country from Point Danger to the Gulf of Carpentaria' before he was elected for Burnett in April 1871.

In December 1872 Bramston married Eliza Isabella, daughter of Rev. Henry Vane Russell, and niece of the marchioness of Normanby, wife of the governor. This marriage may have influenced his final departure from Queensland, for a year later he moved to Hong Kong, where he was briefly attorney-general and then an acting judge. More significant was his work in the Colonial Office which he joined, again following Herbert, in June 1876.

There he served for twenty-one years making good use of his knowledge of Australia. He was created C.B. in 1886 and was registrar of the Order of St Michael and St George from 1892; he was appointed G.C.M.G. in 1900. He also served on special tasks, including a mission to Berlin on the territorial negotiations over Angra Pequena in German South-West Africa in 1886, a royal commission on French rights in Newfoundland in 1898 and a royal commission for a Paris Exhibition in 1900.

He retired at 65 and lived in London till his death. His career is inevitably linked with that of Herbert (even a Brisbane suburb was named Herston after them) and must suffer by comparison with Herbert's greater achievements. Bramston, however, deserves recognition as a brilliant lawyer who proved a skilful, impartial administrator and as typifying the many able Englishmen who contributed to Australian political development.